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Everything You Ever Wanted to Know About Approximate Value

Posted by Neil on May 22, 2012

We get a lot of questions about our Approximate Value system, so I thought it might be a good idea to re-run this explanatory post from December 2010...

Created by PFR founder Doug Drinen, the Approximate Value (AV) method is an attempt to put a single number on the seasonal value of a player at any position from any year (since 1950). The following links will help explain the theory behind the AV system:

Introductory Blog Posts:

  • Part I - this is where Doug explained, in very broad general terms, what his goal was in creating this metric, and what his strategy would be for building it.
  • Part II - this is where Doug explained, in fairly gruesome detail, how the system works for offensive players.
  • Parts III and IV were posted while Doug was fine-tuning the system for defensive players. He invited readers to give opinions on the results.
  • Here are a couple of examples of uses for the method. Studies like these would be hard to do without an AV-like method.

Doug's Brief AV Explanation:

"AV is not meant to be a be-all end-all metric. Football stat lines just do not come close to capturing all the contributions of a player the way they do in baseball and basketball. If one player is a 16 and another is a 14, we can't be very confident that the 16AV player actually had a better season than the 14AV player. But I am pretty confident that the collection of all players with 16AV played better, as an entire group, than the collection of all players with 14AV."

"Essentially, AV is a substitute for --- and a significant improvement upon, in my opinion --- metrics like 'number of seasons as a starter' or 'number of times making the pro bowl' or the like. You should think of it as being essentially like those two metrics, but with interpolation in between. That is, 'number of seasons as a starter' is a reasonable starting point if you're trying to measure, say, how good a particular draft class is, or what kind of player you can expect to get with the #13 pick in the draft. But obviously some starters are better than others. Starters on good teams are, as a group, better than starters on bad teams. Starting WRs who had lots of receiving yards are, as a group, better than starting WRs who did not have many receiving yards. Starters who made the pro bowl are, as a group, better than starters who didn't, and so on. And non-starters aren't worthless, so they get some points too."

Weighted Career Approximate Value

At the top of every player's PFR page, you will see "Weighted Career AV" and a ranking since 1950. This is Doug's way of balancing peak production against raw career totals; for each player, he computes the following weighted sum of seasonal AV scores:

100% of the player's best season, plus 95% of his 2nd-best season, plus 90% of his 3rd-best season, plus 85% of his 4th-best season, ....

And so on. You can read a more detailed explanation of this metric here.

(Note: "Weighted Career AV" should not be confused with "career AV", which is just the unweighted sum of a player's AV scores.)

Similar Players by AV

On a player's page, you may see a table marked "Similar Players". This uses a method Doug invented to find other players who were similar in terms of the quality and shape of their AV career arcs. You can read more about this process here and here.

Where to Find AV on the Site:

4 Comments | Posted in Advanced Stats, Announcement, Features, Pro-Football-Reference.com

Track AL Domination of NL on the B-R Front Page

Posted by admin on May 21, 2012

Over the past few years the AL has really mopped up on the NL during interleague play. With the first weekend of interleague play in the books, you can now view the two leagues head-to-head record on the front page of Baseball-Reference.com (as of today AL is up 23-16, a 95 win pace for a 162 game season). It appears just below the game results on the front page in the middle column.

1 Comment | Posted in Announcement, Baseball-Reference.com

The Lengths Researchers Go To

Posted by admin on May 18, 2012

The following is a report from Richard Malatzky a stalwhart researcher with the SABR biographical committee. There are about 5-10 people on the SABR biographical committee who tirelessly do research to locate late 1800's early 1900's ballplayers. They pore over all kinds of records for no pay to get these records right. We owe them a tremendous debt of gratitude.

With the eventual release of Pennsylvania Deaths Register last month I thought I might find Morelock (ed. for the last 12 years, we've just called him Morelock) but it didn't happen.

I had been searching for him for about 35 years. It turns out that Philadelphia which is where he was from had several Morlocks but no Morelocks, not a one.

The Sporting Life mostly called him Morelock but Morlock did appear a couple of times.

(In the census) There was a Henry or Harry Morlock born November 1869 in Philadelphia and he was a weaver. I figured that this must be him. But what about A Harry? I saw him called A H Morelock a couple of times in Sporting Life. His father was Adam and son was Harry A.

He played several years around Philadelphia and appeared with the Phillies in 1891 and 1892.

Harry was in the census in Philadelphia up to 1930 and appeared in the Suburban phone book in Upper Darby Pa after 1940.

I searched his daughter's name Lillian and surprisingly found her obituary age 106. Lillian G Rathburn. I searched her name and surprisingly found a legal document from Atlantic City NJ that gave her father's date of death April 21 1949 and place Atlantic City. All of his relatives were listed and combined with Lillian's obit I was able to find the addresses of some relatives.

I found that the only newspaper available for an obit in Atlantic City was the AC Press. On a visit to AC, I searched the microfilm and no obit.

Today, I received an e-mail from a great great grandson of Harry who confirmed that this was the ballplayer. He has a picture of him in uniform.

Richard Malatzky

Biographical Committee

3 Comments | Posted in Announcement, Baseball-Reference.com

1984-85 NBA Box Scores

Posted by Justin Kubatko on May 18, 2012

As many of you know, about four months ago we announced that we had posted copies of every box score in NBA history. However, since these box scores were scans we could not create player game logs, compute player splits, etc. As we said in that post, it is our goal to one day have all of these games in a database-friendly format.

Well, I'm happy to announce that the work for the 1984-85 regular season has been completed. Please take some time to check out the box scores, player and team game logs, and player and team splits for the 1984-85 NBA season. Keep in mind that almost all of the scanned box scores are abbreviated (i.e., they only contain field goals, free throws, and points for the players), so there will be many missing values for each game.

5 Comments | Posted in Announcement, Basketball-Reference.com

Happy Belated Birthday to Basketball-Reference.com

Posted by Justin Kubatko on May 15, 2012

Somehow I let this slip by without notice, but last Thursday Basketball-Reference.com celebrated its 8th birthday. I launched BBR as a standalone site on May 10, 2004, but of course it is now part of the Sports-Reference.com family. I still do almost all of the work on the site, so I take great pride in how much it has grown over the years. That growth, of course, would not be possible without our dedicated users, so in addition to the birthday wishes I would also like to extend a warm thank you to everyone who has played a part in making this site what it is today.

9 Comments | Posted in Announcement, Basketball-Reference.com

NY Times: The Numbers Are Adding Up for the Thunder

Posted by Justin Kubatko on May 14, 2012

Here's a link to a piece I wrote for the print edition of Sunday's New York Times:

The Numbers Are Adding Up for the Thunder

Comments Off | Posted in Announcement, Basketball-Reference.com, New York Times

Find Interleague Records and Head-to-Head Histories Using the Play Index

Posted by Neil on May 14, 2012

Did you know that you can use the B-R Play Index to search for information regarding interleague play? With games between leagues starting later this week, here are a handful of PI tricks:

* Search for great single-game or multigame player/team performances using the Game Finders. This lets you find trivia like the all-time winningest career pitchers in interleague play.

* Use the Streak Finders to look for long streaks in interleague games.

* Query franchise head-to-head records using the Head to Head Finder. This allows you to search for lists like the Mets' records vs. each opponent since 1997, which includes all of their interleague games.

* The Situational Finder can search teams' records in interleague games and find items like the teams who had the best interleague records in a single season.

Give them a try, and learn something new about interleague play.

Comments Off | Posted in Announcement, Baseball-Reference.com, Features

2012 Japanese and Independent American Leagues Updated Daily – Baseball-Reference.com

Posted by admin on May 11, 2012

2012 Japan Central League / Japan Pacific League / Atlantic League / Pecos League / All 2012 Leagues Covered

Starting today, we will be updating statistics for Nippon Pro Baseball and American independent leagues, like the Atlantic League, on a daily basis. Hope you enjoy this one of a kind feature on Baseball-Reference.com. Because you know you want to follow Lastings Milledge of the 2012 Yakult Swallows.

All 2012 Leagues Covered

9 Comments | Posted in Announcement, Baseball-Reference.com

Player Twitter Accounts

Posted by Mike on May 11, 2012

As with baseball and basketball, we've now added player Twitter account links to player pages. Let us know if we're missing anybody.

Comments Off | Posted in Announcement, Pro-Football-Reference.com

WAR Comparison Chart by Site- Baseball-Reference.com

Posted by admin on May 10, 2012

WAR Comparison Chart - Baseball-Reference.com

Colin Wyers was kind enough to fill this out for WARP, so I've added WARP to the comparison chart and also split it off onto its own page for easy linking. If you want to know why numbers are different from one site to the next, this explains why.

Comments Off | Posted in Announcement, Baseball-Reference.com

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