On Baseball-Reference, we include a statistic called WPA (Win Probability Added) in our boxscores. The basic definition of this statistic is the "sum of the differences in win expectancies for each play the player is credited with". You can find a deeper explanation on our Win Expectancy glossary page.

Given we're entering the 2018 postseason, we've decided to add postseason WPA calculations to player pages, postseason series summaries and postseason leaderboards. For an individual player, you will find this in the final column of the player's Postseason Batting and/or Postseason Pitching table. For example, here's a link to Mariano Rivera's table, breaking down his career 11.69 WPA in the postseason. If you go to our MLB Playoffs section, all series summaries will now include WPA in the series stats tables.

Our playoffs section also has career and single-season leaderboards which now have sections for WPA. The aforementioned Mariano Rivera leads all pitchers in career postseason WPA, while David Ortiz occupies the top of the career leaderboard for batting WPA in the postseason.

As a reminder, you can also find more detailed regular season win expectancy and win probability stats for players in their Advanced Stats pages, accessible from the Finders & Advanced Stats tab on player pages. If you have any questions or suggestions, feel free to contact us through our feedback form.

Regular Basketball-Reference users are well acquainted with the Play Index, which allows us to compare players across eras and slice and dice season-level data by many criteria. Today we are now introducing the WNBA Player Season Finder, which will be accessible from both the Play Index page and from our WNBA home page. We have WNBA stats back to the league's inaugural 1997 season, which means you can now search all of WNBA history with this tool.

Just like our NBA Player Season Finder, with the new WNBA tool you can do single-season, combined season and total season searches. For example, with the combined season search, you can now create franchise career leaderboards, maybe to see how far ahead in first place Tamika Catchings is among point scorers in Indiana Fever history. Or with the total seasons search, you can now execute a search like players with the most qualified seasons of 2 blocks per game; Margo Dydek and Lisa Leslie lead with nine seasons each finishing with that mark in their career.

Of course, current season stats are also searchable with the Player Season Finder, so you can give them some perspective with past stats. A'ja Wilson is burning up the league in her first WNBA season, currently averaging over 20 points per game. Here's a look at the others in WNBA history who finished with 20 points per game in their rookie season.

Stay tuned for more additions to the WNBA section of our site here on the Sports-Reference Blog. If you have any questions or suggestions, feel free to contact us through our feedback form.

As the 2018 WNBA season continues on through the summer, we have now added an Advanced Stats section to the season stats pages. We already included advanced stats on players' individual pages, so you already knew Brittney Griner had a 10.2 block percentage during her 2015 Defensive Player of the Year performance, but now you can see her performance with the context of the rest of the league. You could also take a look at the gap in win shares between Nneka Ogwumike's 2016 MVP season and the rest of her peers. Of course, we'll continue to update 2018 advanced stats along with the classics as this season unfolds.

I've been at this for 18 years now. Baseball-Reference.com launched in early April of 2000, and 18 years is a long time. We've gone from pre-formatted plain text tables to html tables, through various logos, and several redesigns involving mobile designs. Along the way, the only consideration has been what would work best for the user. That's why, after months of extensive research, I'm very pleased to announce:
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As you browse Baseball Reference, you might notice some subtle changes to WAR figures on the site. There are four main reasons for this:

1. Park factors for recent seasons have been re-computed to be three-year rolling averages. For instance, 2016 Park Factors now encompass 2015-2017. This is something that needs to be done when seasons end.
2. We've incorporated restated and expanded fielding statistics from Sports Info Solutions. SIS's Defensive Runs Saved forms the basis for our Defensive WAR calculations since 2003. From 2011 on they recalibrated data using their timer measures to measure ball hang time. There was also some recalculation based on changing shift methodology. Though we're now publishing their catcher framing stat (Strike Zone Runs Saved), we have not incorporated it into WAR at this time.
3. Pitchers who received time as position players (whether PH or in the field) are now being treated as part-time pitchers and part-time position players. Previously we treated them as full-time pitchers. Some pitchers like Red Ruffing, Bob Lemon and Jim Kaat appeared in many games as a position player, pinch hitter or pinch runner. We used to credit these PAs as pitchers, which overvalued their offensive contributions. To handle this, we compute a percentage of time as a non-pitcher and make an adjustment.
4. Also, we have incorporated a good deal more Retrosheet data which has affected the years we can compute more advanced fielding and baserunning measures. We're now able to roll these measures back to 1953. Another important change is that with Retrosheet gamelogs back to 1908, we can now use their IP data back to that year to get starter/relief IP splits. Some pitcher WAR changes for 1908-12 are due to WAR now being calculated using gamelog IP rather than the "official" total listed on the player's stat line. The biggest difference here was the appropriately named Bugs Raymond. The "official" record credits him with 324.1 IP that season, but the gamelogs come out to 304.1, which significantly impacted his WAR calculation (see below). For further reading on discrepancies between "official" records and more recently produced gamelogs, please read this excellent explainer by Retrosheet's Dave Smith.

For further details on WAR and its calculation, please see this WAR explainer.

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Our friends at Sports Info Solutions (formerly known as Baseball Info Solutions) have provided us with a pitch framing measure back to 2011, which we have added to Baseball Reference. Before I explain any further, if you're unfamiliar with the concept of pitch framing please read Mike Fast's 2011 article on the topic and Ben Lindbergh's 2013 follow up.

The stat that we have added is called Strike Zone Runs Saved. It represents the runs saved by catcher framing. In our tables, it's labeled RszC and it's available from 2011 to the present. While this statistic is a potential component of Defensive Runs Saved (and therefore WAR), please note that we have elected to not integrate this number into DRS (or WAR) at this time. We may elect to do so in the future, but for now we agree with Bill James's stance that waiting for further research is a good idea.

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At Hockey Reference, we calculate adjusted stats in order to more accurately compare players from different eras and different goal scoring environments. With Alex Ovechkin approaching his 600th career goal, there has been some chatter about Ovi being the greatest goal scorer in NHL history.

So we thought this made for a good time to introduce the adjusted scoring statistics into the Player Season Finder tool in order to test this hypothesis. As it turns out, Ovechkin is easily the NHL leader in "adjusted goals" through 13 seasons of play. If you click on the link, you'll see he has 691 adjusted goals (through 1/15/18), while Wayne Gretzky had 607 adjusted goals through 13 seasons.

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With last week's announcement of the 2017 All-Pro teams, we're pleased to report that we've added 2017 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 Pro Bowl rosters are finalized. However, there's already some interesting preliminary information to dig through.

As of right now, Tom Brady and Todd Gurley are co-AV leaders at 19. For Brady, this represents the best season in NFL history by a player in his 40s. Gurley, meanwhile, is the youngest RB to hit that mark since Steven Jackson in 2006.

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. For this year's full AV leaderboard, go here.

This article assumes a lot of prior knowledge about the discussion of Wins Above Replacement, you can catch up here

• How Baseball-Reference.com calculates WAR and how others do:
  WAR-Wins Above Replacement Explanation
  WAR-wRAA explanation
  WAR-Position Players
  WAR-Pitchers
  WAR-Runs to Wins (this is especially relevant)
  Competing WARs Comparison Chart
• My Answer to “I Don’t Like How Complicated WAR Is and How It Is Constantly Changing.” “WAR is Like GDP for Baseball”
• Bill James: Judge and Altuve, and then
  Bill James: MVP Followup
  Joe Posnanski: More on WAR, following up on Judge and Altuve.
• Dave Cameron's reply to James: Putting WAR in Context: A Response to Bill James
• Jonathan Judge at Baseball Prospectus wrote an excellent piece on variability in WAR: Prospectus Feature: Bill James vs. The Noise
• Bill James and I discuss on twitter what I think is the crux of the matter
• Rany Jazayerli on how WAR should handle luck

First off, none of us are here without Bill James. We are all at our very best merely Chaucer or Joyce to his Shakespeare. All sabermetrics predating him flowed into his work and all sabermetrics after him carries echoes of his work.

To the discussion at hand.
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When we launched our new site three months ago, one of the casualties was the neutralized stats tables we printed on player pages. Those tables were originally built using code that had grown increasingly unwieldy and were not something we'd be able to adequately maintain moving forward. That said, we're happy to announce that we have rebuilt these tables and added new features, as well.

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