Sports Reference Blog

Just in time for the 2020 postseason, Baseball-Reference has added championship win probability added (cWPA) and championship leverage index (cLI) to the site.

Just as single-game win probability added (WPA) measures how a player impacts their team's chances of winning a game, cWPA measures how a player impacts their team's chances of winning the World Series. Similarly, championship leverage index uses the same concept of single-game leverage index (LI), but expands the scope to measure the importance of a particular play, in how it impacts a team's chances of winning the world series.

These stats are highly dependent on context and are best used as "story stats" rather than determining which player was better. When telling the story of the history of baseball, we point to the greatest moments such as Bobby Thomson's Shot Heard 'Round the World, Bucky Dent's home run over the monster, David Freese's clutch performance in Game 6, or Madison Bumgarner's Game 7 performance. Moments like these are captured in cWPA and cLI, but it's not just history's greatest moments. Every event in our play-by-play database has a value.

How are cWPA and cLI calculated?
Let's look at Bobby Thomson's Shot Heard 'Round the World for example. This was the third and final game of the National League tiebreaker series. A win for the Giants would clinch the pennant with a 50% chance of winning the world series. However, a loss would end their season, meaning a 0% chance of winning the world series. The difference between a win and a loss in this game is 50%. To get the championship leverage index, we simply divide .5 by our baseline of .006 (The baseline is explained here). This means that the Giants' cLI for the game is 83.33 (.5/.006). The LI for Bobby Thomson's final at-bat was 4.74. To get the cLI for the at-bat, we simply multiply the game cLI by the at-bat's LI, which gives us 395.0 (83.33*4.74). This mean's that this at-bat is 395x more important to the Giants' chances of winning the world series than the average play on opening day.

When Thomson stepped to the plate, the Giants were down 3-1 with 1 out in the bottom of the 9th, giving them just a 29% probability of winning the game at the start of the at-bat. Since the home run ended the game, the probability of winning the game at the end of the at-bat was 100%. To get the cWPA for the play, we multiply the difference between game win probability at the start and end of the at-bat by the difference between the championship win probability of a win and a loss. This gives Thomson .355 cWPA ((1.0 - .29) * (.5-0)). This means that Thomson's home run increased the Giants' probability of winning the world series by 35.5 percentage points. On the flip side, the opposing pitcher Ralph Branca is given -.355 cWPA for the play.

Note: cWPA values are displayed in percentage format, so the example above displays as 35.5%.

There are currently a number of places to find cWPA and cLI on Baseball-Reference:
Regular Season Leaderboards: Career Regular Season Batting Leaders
Postseason Leaderboards: All-Time Batting Leaders
Batting and Pitching Game Logs: Yaz's amazing 1967 season
Batting and Pitching Win Probability Tables: Sandy Koufax's Pitching Win Probability
Postseason Series Pages: 1991 World Series
Box Scores: 1960 World Series Game 7
League Batting and Pitching Win Probabiliy Pages: 2020 MLB Batting cWPA
Team Batting and Pitching Win Probability Tables: 1975 Reds Batting
Team Schedules: 1978 Yankees

If you have any questions or feedback on this new feature, feel free to contact us through our feedback form.

In previous months, we have launched Stathead Baseball, Stathead Hockey and Stathead Basketball. Today, we're thrilled to announce that Stathead Football has joined our suite of Stathead tools, the most powerful set of sports research tools available to the public. In fact, they're so good that the pros (whether they're running teams or covering them) also swear by them.

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In February Basketball-Reference added a list of every Game-Winning Buzzer-Beater in NBA history. Today, we're happy to announce that we've also added a list of every Game-Winning Buzzer-Beater in ABA history.
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Sports Reference LLC has acquired the Baseball Gauge from owner Dan Hirsch. Dan was hired as a developer by Sports Reference in 2018 and has spearheaded our work on fbref.com. This week, Dan migrated The Game-Changer from the Baseball Gauge to a new home on Baseball-Reference.com. Work is continuing on the migration of additional features like Championship Probability Added and Championship Leverage Index.

Following the re-launch of these features on Baseball-Reference.com, The Baseball Gauge will be shut down. You can follow Dan on Twitter.

Baseball Reference is happy to announce the launch of the Game Changer tool, which allows you to customize how you view baseball on MLB.TV. The Game Changer may be familiar to those who were using it when it was hosted by The Baseball Gauge, a site run by Dan Hirsch who has adapted the tool to work from Baseball Reference now. The Game Changer functions in a similar way to the NFL RedZone channel, but for Major League Baseball, prioritizing the key moments you want to catch. All you need to do is set your priorities and click "Launch Video". The Game Changer will do the rest by automatically switching to the game that meets your highest priority at that moment.

Some of the different priorities you can set include:

- If a pitcher you want to see is on the mound pitching

- If a batter you want to see is at bat
- There is also an option to switch to the game if that batter is on deck with less than 2 outs

- If a player you want to see is on base

- If the game situation is high-leverage, meaning it could have a big effect on the team's chance of winning

- If there's a no-hitter going through x innings

- If there's a position player pitching

- If a game has entered extra innings

This is currently not available on mobile. So, if you have MLB.tv access on your computer and wanted a way to personalize your watching experience, check out the Game Changer and give it a try! Feel free to send any suggestions or feedback through our feedback form, we'd love to hear your thoughts on this new tool.

Thanks to work from summer intern Amy Huddell and the research of APBR President Emeritus Robert Bradley, Basketball Reference has greatly expanded its database of gap years for NBA players. Specifically we've added 704 new records in addition to the previous gap year data we had on the site. This includes mid-season career interruptions, first-season injuries and situations where they were still on the roster for their final season but did not play.

Often mid-season career interruptions are injury-related, such as Derrick Rose's ACL in 2012-13 or Greg Oden's various knee ailments. Occasionally there are other reasons like Robert Reid in 1982-83 voluntarily retiring to pursue the ministry or Red Morrison in 1956-57 who went into the construction business before making a return the next season. There are a couple of players such as Charlie Paulk and Dick Rosenthal who had gap years due to military service.

Notable end-of-career notes that we've added include Wilt Chamberlain sitting out his final year under contract with the Lakers and Alex Groza being suspended indefinitely for his involvement in the CCNY point shaving scandal.

Another gap year situation is players in international leagues between getting drafted and making their NBA debut, or players extending their careers internationally. Recent examples of this that were added in this batch include Patrick Beverley and Stephon Marbury.

We hope that adding this context to player pages helps people browsing the site understand their careers a little better. Thanks again to Amy Huddell and Robert Bradley for their help with this project. If you have any questions or suggestions, feel free to contact us through our feedback form.

We are proud to announce that FBref has added an enormous new data set, containing over 60,000 match reports, to our site. This represents a major update that takes our coverage of major leagues like the Premier League, Bundesliga, La Liga, and Champions League to the next level.

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With Major League Baseball making a mad dash to complete the 2020 season, a number of norms and standards have gone by the wayside this season. Due to postponements, cancellations, and Canada's need for a quarantine of those playing America's Pastime, MLB has been forced to schedule what they've considered home games to be played on the road. In these games, the host team bats first and they often go through the charade of wearing their road unis while the traveling team wears their home whites. We handle these games in a certain way and this has led to confusion as to what the home and road records and splits represent on Baseball-Reference.com.

Our policy has been and remains that a team playing in their home park is the home team regardless of whether they bat first or second (we call these Home Team Batted First or HTBF). We feel that home and visitor refers to location and not batting order. In a neutral site game (of which there have been very, very few), the home team would be the team to bat last. Since 2007, there have been 19 games where the home team batted first, those are listed below.

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Today Basketball Reference is excited to announced the debut of the most powerful set of publicly available research tools on the hardwood. We're calling it Stathead Basketball and you can sign up for a free month of access here. Most of these tools may be familiar to some of our users from the Play Index. But Stathead also comes with the first of what will be many new additions: The Player Quarter Finder, which allows users to find the best performance in a quarter, or groups of quarters, since 1996-97.
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The 2020 WNBA season will begin this weekend, and Basketball Reference continues to bolster our coverage of this league, this time with the addition of player splits. This includes splits by season as well as career splits, accessible from any player's main page. Using Emma Meesseman's career splits as our example, you can see this includes home/road splits, starter/reserve splits performance in wins vs. losses, results by opponent, days rest, and breakdown by minutes played in the game.

Another smaller addition we've made is adding a stat summary to the top of player pages, giving you a quick look at the player's stats for their entire career and their most recent season. We plan to keep working on expanding our WNBA coverage, and we hope you check in with us as you follow the 2020 season! If you have any questions or suggestions, feel free to contact us through our feedback form.