A Trip to Baseball-Reference.com: Positive WPA Streaking

I often take trips over to Baseball-Reference.com to poke around aimlessly, but it is not that often that I find something interesting enough to write up here, but last night I did find something quite cool that I'd like to share.

We all remember Jose Bautista, right? He was the Toronto Blue Jays' best hitter until he got hurt this season. Yea, that guy. He had a tremendous start to the 2011 season: in April and May he hit .363/.505/.786 (1.290 OPS!) with 20 HR. That's pretty amazing for sure, but for a period of time, he was so hot that he recorded a positive WPA for 16 straight games, which is the third longest such streak in Major League Baseball history.

For those of you who are not familiar with the stat, WPA stands for win probability added. You can click here to read about WPA over at the Fangraphs Glossary, but to boil it down it is a rough measure of how much a particular batter or pitcher has contributed (either positively or negatively) to the results of their team's game. Sabermatricians have calculated the probability of a particular team winning the game (its win expectancy) for every possible game situation.

By comparing a team's win expectancy before and after each of a batter's plate appearance we can calculate how much he has contributed in the game. The same thing goes with pitchers, looking at each plate appearance against them. A player having a good game will have a positive WPA, and if he adds 10% or more in win expectancy for a game (ie. WPA >= +0.100), he gets a Jay of the Day! award here on Bluebird Banter.

Normal, human, batters have good games and bad games so even really good batters will record a negative WPA every few games. Not Jose Bautista, though, at least in the 16-game stretch from April 25 and May 18, 2011. During that stretch, he got was a Jay of the Day! 10 times, his highest WPA was +0.328 and his lowest was +0.018, and he hit .386/.539/.947 with 9 homers and 17 RBI.

The streak of 16 straight games with a positive WPA surpassed the previous franchise record of 12, which was held by Aaron Hill in 2009. Lloyd Moseby and George Bell both recorded 11-game streaks in 1987.

Jose Bautista was two games away from tying the Major League record jointly held by J.D. Drew (for the Atlanta Braves in 2004, hitting a scorching .418/.518/.851 in that stretch) and John Stearns (for the New York Mets in 1977, hitting a more pedestrian .426/.500/.770). Willie Mays (1964), Wayne Garrett (1970), and Brooks Robinson (1971) have had 17-game streaks.

Bautista's 16-game mark is shared by some great names: Willie Mays (1965), Pete Rose (1968), Carl Yastrzemski (1970), Manny Ramirez (2002-2003), Barry Bonds (2004), and Ryan Howard (2009-2010).

It is easier for pitchers, especially (good) relievers, to record long strings of positive WPAs. This season, Darren Oliver had a 15-game streak between June 3 and July 7, and Casey Janssen recorded a 14-game streak between April 27 and June 3. The franchise record is 27 games, held by Duane Ward (1992-1993), followed by Tom Henke (surprise, surprise) who has a 24-game streak. The Major League record belongs to former Cleveland Indians closer Jose Mesa who had an incredible stretch of 49 WPA positive games between 1994 and 1995.

Other names near the top include Roberto Hernandez (40, 1995-1996), Dennis Eckersley (39, 1991-1992), John Axford (38, 2011-2012). The great Mariano Rivera weighs in with a 35-game streak between 1999 and 2000.

Looking at starters, the franchise record for longest streak of starts with a positive WPA belongs to Dave Stieb (1982-1983) and Juan Guzman (1991-1992), who had 14-game streaks. Coming from behind are Roger Clemens (13, 1998), and Roy Halladay (11, 2009 and 10, 2006-2007). Pedro Martinez has the Major League record with 23 in 1999-2000, with Johan Santana (22, 2004) right behind.

Research was done using the Play Index of Baseball-Reference.com. To calculate an official game for a batter for the streak, he must have made at least one plate appearance. WPA data is available for all games between 1918 and August 15, 2012. I'd like to thank Beer Leaguer for asking the question on Twitter that led me to do this research.