Sports Reference Blog

As we approach the beginning of the 2021 season, we have made some updates to our Wins Above Replacement calculations. You may notice some small changes to figures as you browse the site. As always, you can find full details on how we calculate WAR here.

Defensive Runs Saved Changes

Last week, we updated Defensive Runs Saved (DRS) totals across the site with new figures from Sports Info Solutions that incorporate more accurate hit timing data. This impacts some fielders from 2017 to 2020. You can read more about the updates in the Sports Info Solutions blog, including which teams and fielders were most impacted.

2019 Park Factors

Park factors for 2019 have been re-computed to include the 2020 season, since WAR uses a three-year average for park factors when computing pitching WAR. The most significant change here is the Cincinnati Reds, whose pitching park factor rose from 103 to 108 (where <100 represents a pitcher’s park and >100 represents a hitter’s park). Luis Castillo sees the biggest benefit from this, with his 2019 WAR rising by 0.7 wins. All other changes to pitching WAR from updated park factors are smaller than Castillo’s 0.7 WAR gain in 2018.

2020 Park Factors

When a season is in progress, our three-year average park factors are computed using a prorated combination of the current season and two years prior. Due to the shortened 2020 schedule, the park factors for 2020 were still using some data from 2018, because the 60-game schedule was being treated as a partial in-progress season. We’ve addressed this in our park factor calculations so that the 2020 park factors only include 2019 and 2020. This change was reflected in OPS+, ERA+, Rbat+, and rOBA in the past week, but it is now also incorporated in WAR, leading to small changes for a handful of players.

Lance Lynn gains the most from this, adding 0.3 wins with Globe Life Field moving from a slight hitters park (102) to a more extreme hitters park (107). Trea Turner has the largest change on offense, also gaining 0.3 wins with Nationals Park moving from being a slight hitters park (102) to being a slight pitchers park (98).

New Game Logs from Retrosheet (1901-1903)

Last summer, we updated the site with new data from Retrosheet, including new game logs for players from 1901 to 1903. Having game-level data allows us to be more precise in our WAR calculations, since we can consider the specific ballparks a pitcher played in and the opponents he faced.

We presented a more in-depth example of this in our last WAR update, when Hall-of-Famer Christy Mathewson’s WAR rose after we added new game logs. This time around, pitcher Doc White saw the biggest change, gaining 1.5 WAR over the course of his career.

Biggest Career Movers

The top mover for position players in career WAR is Trea Turner, gaining 1.8 wins through a combination of additional runs saved and beneficial park factor changes. Trevor Story is close behind at 1.7 wins, primarily through additional runs saved.

On the pitching side, we see Doc White with 1.5 wins gained as described above. Among modern players, Patrick Corbin saw his career total drop by 0.8 wins. This is the flipside to how Turner gained credit. Corbin is debited for playing in a more pitcher-friendly park than previously thought, and for playing in front of defenders like Turner who are getting additional credit for their defense. Both of these changes decrease the number of runs we’d expect Corbin to have allowed, and as a result his performance is not as valuable as previously calculated.

We’ve highlighted some of the more extreme changes here, but to see full lists of the largest changes to season and career WAR totals, please see the spreadsheet here.

Thanks to Baseball Info Solutions and Retrosheet for their contributions. Please let us know if you have any comments, questions or concerns.

On Tuesday night, we added a new table of Advanced Stats to player pages.

This is what it looks like for hitters:

And for pitchers:

Rather than simply explain what we added, I’m going to describe how we added it. How does something go from an idea to a feature on Baseball-Reference? The entire process starts with you, the user.

At the beginning of January, we began conducting interviews with several users to discuss their experience using Baseball Reference and Stathead. By the time we launched the feature, we had spoken with nearly 50 users. It’s important to note that when we started the interview process, we didn’t have a particular solution or even a particular problem in mind.

There were several goals for these interviews. We wanted to find:

1. What is the general perception of Baseball Reference compared with other sites?
2. What features would users like us to add to Baseball Reference?
3. What features would users like us to add to Stathead?
4. What features of Baseball Reference and Stathead are users having a hard time using, finding, or just remembering to find?
5. In what ways are people using our sites that we hadn’t anticipated?

Many of the interviews confirmed what we already knew. But every interview had at least one piece of gold that we could learn from. One interview in particular stood out to me and sent me on a path towards designing the feature you see on the site today.

I spoke with Mark Gorosh (@sportz5176 on Twitter) on February 3. Mark was lamenting that we don’t have advanced metrics such as BB% and K% on Baseball-Reference player pages. He didn’t understand why we had so many columns about the inner workings of WAR (in the Player Value table), but not established advanced stats like walk rate.

The issue, of course, is that we do have those stats. At this point I showed Mark the Advanced Batting page and… I’m not going to say Mark yelled at me, but he gave us some tough love that we really needed to hear. He couldn’t understand why all these great stats were not on a player’s main page.

And he was right.

There were a few different paths we could take.

1. We could take all of the tables on the Advanced Batting pages and put them on the main player page. This wasn’t practical, however. There’s also an Advanced Fielding page and, of course, and Advanced Pitching page for pitchers. Adding all of these for a pitcher would lead to dozens of tables. Having so much on one page would negatively affect user experience.
2. We could pick and choose certain things to bring over to the main page. Perhaps we could do this in a way that also leads users to click to the Advanced pages.
3. We could move nothing, but focus on doing a better job of directing users to the player sub-pages (such as advanced batting and pitching, splits, and game logs).

We opted for the second option, but will also be looking to address the third option. The solution for the immediate job at hand is getting some advanced stats on the main player pages. But the fact that Mark (and other users) didn’t even know we had these advanced stats is a symptom of another issue—some users either are not noticing these sub-pages or they know about them but don’t think to use them (because they’re a click away).

This is a big deal because Baseball-Reference has a lot of users, but the super-users are the ones that have discovered the game logs, splits, and other advanced features. From there, they move on to Stathead to get even more powerful tools for their research. We want as many users discovering those features as possible so they can also turn into power users. So, in the future I’ll be looking to improve the player (and team and league) sub-navigation.

Now that we chose the path to explore, there were still different ways to proceed. One was to move the Player Value table (where we show WAR and its components) to the Advanced Batting page, but bring the most important columns (such as WAR, WAA, oWAR, dWAR, etc.) along with the most important columns from other Advanced Batting tables.

We began testing with that.

This early mockup tested well but some users showed a very strong preference for keeping the Player Value table where it was and adding a separate Advanced Stats table below it. Honestly, that was probably the right solution all along, but I wanted to see we could solve this without increasing the number of tables on player pages. We ended up adding one, but that’s fine.

There were several key things from this mockup that tested well, such as:

1. The collection of stats we chose (which were the result of team discussions and also a survey we shared on Twitter).
2. The addition of rOBA (our version of wOBA—Reference weighted OBA) and Rbat+ (our version of wRC+—based on the Rbat used in WAR). Despite the fact that these stats are brand new, I was impressed by how many guessed right away what they were.
3. The links under the table to let users quickly jump to any table on the Advanced Batting page from the main player page. Not only does this help raise awareness of the Advanced Batting page, but also lets users know what tables are specifically on the page before they even go there.

The next version we tested kept all of these features, but put them in a separate Advanced Batting table. We also added base-running data, more batted ball data (such as the oft-requested Exit Velocity and Hard Hit %), and a row to display league averages for each stat (because users may not know what a good XBT% is).

That version of the mockup looked much like what you see today:

This version tested exceedingly well. Now it came down to building it. I asked Kenny Jackelen (@kennyjackelen on Twitter), Baseball-Reference’s developer, for a summary of the development process for a new feature like this. Kenny said he:

1. Iterated multiple times with the team internally to get feedback on the table implementation (including how the table should render for players from different eras).
2. Created new database tables for exit velocity data (which also powers the Hard Hit %)
3. Added columns to existing tables to store rOBA and Rbat+ more permanently (previously these calculations were done as an intermediate step to get to WAR, so the database structure needed some updates to make it easier to pull them into the page-building process alongside other stats).
4. Added logic to our play-by-play processing to assign batted balls a Pull/Center/Oppo location so that we can get a count of each type and compute the percentages for the Advanced Batting table
5. Read a lot of slack messages in ALL CAPS from Adam D—like a marathon runner being handed a cup of water.

When it was ready, I got Mark back on Zoom to see his reaction. He said “it’s a 10.” He elaborated further, saying “It's not enough to be baseball’s best data aggregator. You have to present the information in a way that fans will be able to find it. I was honored that BRef and Adam took my suggestions to heart. The new player page designs put so many great pieces of data in easy to find places… near the top of the page.”

As a researcher, it was very fulfilling to come full circle with Mark. He went from tough love to delight.

As helpful as it was, not all user interviews revolve around tough love. Many users I have spoken with weren’t sure what to expect when they hopped on a call. Far more often than not, it’s just a casual conversation about baseball, the different ways people use the site, and what they’d like to be able to do.

I asked interview subject Jim Passon (@PassonJim on Twitter) if he had any thoughts on the interview process (so you don’t just have to take my word for it). He said “When Adam reached out to me to have a conversation about features that I’d like to see in the future, I couldn’t get the meeting set up quick enough. As expected, the meeting was awesome! I got to make a few suggestions, learn some new tricks, and catch a glimpse of the cool features that were already being developed for the site (which I absolutely loved). I now feel like I’m a part of my favorite site on the web... and that feels pretty good!”

Interviewee Jessica Brand (@JessicaDBrand on Twitter) echoed a similar sentiment, saying “I felt at ease, just discussing sports in depth in every which way with friends. It’s a great way to get those endorphins going to see and meet up with friends at your local stadium/arena/pitch you can’t necessarily see because of social distancing. Interviewing with Adam and Kenny provided the same warm and fuzzies.”

And honestly, in this time of social distancing and quarantine, hopping on the phone to talk about Baseball Reference with some of my favorite writers and analysts has been incredibly fulfilling. If you’d like to chat with me about how you’re using Baseball-Reference and Stathead, feel free to reach out at @baseballtwit on Twitter or go ahead and book a time on my calendar to chat.

February 25, 2021

Sports Reference LLC is pleased to announce that they have purchased the historical, statistical databases of Pete Palmer, Ken Pullis and Gary Gillette. This includes full historical databases for

Major League Baseball,
the National Basketball Association,
the National Hockey League, and
the National Football League.

Since their launch in 2000, the Sports Reference sites have presented and relied upon the groundbreaking and painstaking work of Palmer, Pullis and Gillette. Palmer’s pioneering work in baseball statistics has made his database the gold standard in the field, and his work with John Thorn on the Hidden Game of Baseball and Total Baseball is legendary. Pullis’s award-winning work in the field of pro football statistics formed the basis for the ESPN Pro Football Encyclopedia--the last pro football encyclopedia ever printed. Gillette created and edited the ESPN Baseball and Pro Football Encyclopedias and compiled a set of unique MLB databases for subjects like the Disabled/Injured List that previously had never been covered.

We are excited that we will now be the stewards of these databases. We intend to build upon Ken, Pete and Gary's extraordinary work. At Sports Reference, our purpose is to answer questions, so our users can grow their appreciation, understanding, and love of the game. Owning these databases will allow us to continue doing that, but also open up potential new opportunities such as making free databases available for researchers and publishing new products incorporating these datasets.

We are honored that Pete Palmer and Ken Pullis will continue the work on their databases as consultants to Sports Reference and look forward to expanding the scope of what is known about the history of North American sports. We will also be working with Gary Gillette on several special baseball projects in the future.

Sports Reference LLC is based in Philadelphia, PA and serves millions of users a month through its websites: Baseball-Reference.com, Basketball-Reference.com, Pro-Football-Reference.com, Hockey-Reference.com and others.

Pete Palmer is a titan in the field of baseball research and history and has been one of the foremost chroniclers of the National Pastime for the past five decades. He has edited or contributed to virtually every baseball encyclopedia that has been published in the last 50 years. Along with John Thorn, Palmer served as co-editor for seven editions of Total Baseball. Along with Gary Gillette, Palmer served as co-editor for five editions of the ESPN Baseball Encyclopedia. Palmer was also the co-author with Thorn of the seminal 1984 analytics book The Hidden Game of Baseball—a landmark work republished by the University of Chicago Press in 2015. Along with Gillette and Pullis, he served as co-editor of the ESPN Pro Football Encyclopedia. Palmer is also known as co-author of The Hidden Game of Pro Football and as a contributor to Total Football. He lives in Hollis, New Hampshire.

Gary Gillette is the founder and current chair of the Friends of Historic Hamtramck Stadium, a nonprofit that is working to restore the former Negro League ballpark near his home in Detroit. Gillette also served for a decade on the Tiger Stadium Conservancy’s board of directors. He has four decades of baseball research, writing, and editing experience, beginning with his work with Bill James and Project Scoresheet in the mid-1980s. A contributor to six editions of Total Baseball, Gillette later designed and co-edited with Pete Palmer the five editions of the ESPN Baseball Encyclopedia. Gillette also designed the ESPN Pro Football Encyclopedia and served as executive editor for both editions of that reference work. A former member of the Society for American Baseball Research’s (SABR) board of directors, Gillette is a past co-chair of two of SABR’s major research committees—the Business of Baseball Committee and the Ballparks Committee. He was the founder and president of SABR’s Detroit Chapter and is now the chair of SABR’s new Southern Michigan Chapter.

Ken Pullis is a retired air traffic controller and former US Air Force pilot. He has had a lifelong interest in pro football statistics and began doing original research in the late 1980s. Pullis is the 2002 PFRA Ralph Hay Award winner for Pro Football Research and Historiography and was co-editor with Gillette and Palmer of the ESPN Pro Football Encyclopedia, volumes 1 and 2. He currently resides in Vermilion, Ohio.

We've been listening to requests for new features from our users and we're happy to announce that we have launched a new tool for Stathead Basketball subscribers: The Player Span Finder.

The Player Span Finder is a powerful research tool that allows you to search and compare player stats based on spans of seasons, games, and days. You can further refine the search to specify the starting or ending point of the span (season, career, or stint with franchise). Finally, with this new tool you can win every debate about the fastest/slowest players to a milestone stat, based on the number of games or age.

Here's a few examples of each type of search to get you started (please note that some searches may take up to 30 seconds):

Most Assists in a Two-Season Span
Most 3-pt Field Goals Made in a 10-Game Span
Most Points in a 30-Day Span
Youngest to 1,000 Rebounds among Active Players

We hope you enjoy this addition to Stathead. If you're interested in a subscription to the service, you can sign up for a free trial here!

We have added some new tables to Basketball Reference that will let you see how a particular team performs by referee assigned for their games. This information is available on both referee pages as well as team season pages in their More Pages tab.

Using Haywoode Workman as an example, if you scroll down to the Teams table, you can see different stats being tracked include win-loss record, pace, free throw attempts and fouls called. Here's a link to the 2019-20 Philadelphia 76ers Referees page for an example of how this looks for a full team season.

We are able to display this referee data back to the 1996-97 season. So find your favorite team, or scroll through the list of referees, and check out this new feature! If you have any questions or suggestions for future additions to the site, feel free to contact us via our feedback form.

FBref is happy to announce the release of a feature we've been excited about for a while, player Scouting Reports that give you a quick look at how players compare in various statistics to other players at their position. This is currently available for players in the Big Five men's European leagues (example: Mohamed Salah), Major League Soccer (example: Diego Rossi) and the Women's Super League (example: Sam Kerr). We show 20 categories on the main Scouting Report at the top of a player's page, selected based on feedback from user research and industry experts, but you can also click through to a Complete Scouting Report which shows many more categories to compare the players by.

In addition, we have added a Similar Players table which locates the players that have the most similar percentiles in the stats used in the Scouting Reports. That table also offers Compare links which takes you to our Player Comparison tool so you can see the players' statistics side-by-side.

For more information on how the Scouting Report works, we have a longer explainer on FBref. This would not be possible without the wide array of advanced stats provided by Statsbomb, so thanks to them.

Depending on how people react, we could even adapt this feature for our other Sports-Reference sites in the future. Because of that, we are eager to hear people's thoughts on this new feature, so feel free to contact us via our feedback form.

Following the introduction of the Team Split Finder last November, we are now proud to announce the addition of another new tool for Stathead Football subscribers: the Player Split Finder.

This powerful tool allows users to search through our splits database to compare players across various situations, with most stats going back to the 1994 season. Here's a quick look at the different splits available and some examples to help you get started.

QUARTER: Most 4th Quarter TD Passes Thrown This Season

LOCATION: Highest Passer Rating on the Road in a Single Season (min. 100 attempts)

DOWN: Most Times Sacked on Third Down This Season

YARDS TO GO: Most Rushing First Downs on Plays with 10+ Yards To Go This Season

DOWN & YARDS TO GO: Best Completion Percentage on 3rd Down and 10+ Yards to Go in 2017

FIELD POSITION: Most Red Zone Targets This Season

SCORE DIFFERENTIAL: Most Pass Attempts When Trailing in 2019

GAME SITUATION: Most Passes Intercepted While Tied with Less Than 4 Minutes Remaining Since 1994

SNAP TYPE & HUDDLE (since 1998): Most Passes Completed Under Center This Season

PASS RUSH TYPE (since 2018): Best Passer Rating Against the Blitz This Season

We hope you enjoy this addition to Stathead. If you're interested in a subscription to the service, you can sign up for a free trial here. We built this tool thanks to feedback from users like you. Should you have any questions or other feedback, please reach out to us.

With the season concluded, we're pleased to report that we've added 2020 Approximate Value (AV) numbers to the site for all NFL players. Note that these numbers are just provisional right now; the final numbers will be released after the All-Pro teams are announced.

As of now, Josh Allen, Aaron Rodgers and Russell Wilson are tied for the league AV lead at 18, with Derrick Henry and Aaron Donald the two non-QBs to make the top 10. You can see the top players in this Stathead.com Player Season Finder search. Washington rookie Chase Young had an especially strong year, finishing at 13 AV. Only Ndamukong Suh and Jevon Kearse had as high an AV among rookie defensive linemen in the post-merger era.

Not sure what AV is? To learn more about PFR's attempt to put a single number on each player-season since 1960 (for the purposes of comparing players across position and era), check out this link. Feel free to send us feedback via our site's form.

Katie Sharp has joined Sports Reference and will be working both on social media and customer success for our Stathead subscription service. Katie spent seven years as a researcher with ESPN's Stats and Info Group, and since then has worked as a writer, editor and researcher on dozens of articles and books. Most recently, she has been a recurring guest on Jomboy Media's Talkin' Yanks podcast. Katie graduated from Williams College and also has an MBA from the University of Oregon. She's on twitter at @ktsharp.

Per-36 minute player projections are now live on Basketball-Reference for the 2020-21 season. These projection are 'simple' projections using the Marcel the Monkey system.

Marcel's keeper, Tom Tango, describes the system as follows:

"[I]t is the most basic forecasting system you can have, that uses as little intelligence as possible. So, that's the allusion to the monkey."

So there is no consideration for injuries, change of scenery, etc., in these projections.