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WPA To Date

by Dave Studeman
May 10, 2007

If you've hung around here for a while, you probably know about Win Probability Added. It's simple, it's straightforward and it's unlike any other baseball statistic. It's not the be-all and end-all of baseball numbers, but it's fun, it's insightful—why, it's baseballtastic!

That's why Fangraphs has made WPA the centerpiece of its website. You can find every player's WPA and Leverage Index (a measure of the importance of a plate appearance to the game's outcome) on Fangraphs, as well as team totals and game graphs, for the past five years. It's simply awesome stuff, giving Fangraphs a virtual tie with Baseball Reference for best baseball stats site, in my book. Of course, I kind of like the Hardball Times' stats, too.

Anyway, I spent some time poking around Fangraphs this week, and came up with the following WPA facts and rankings (as of Tuesday).

Batting WPA

On a team level, batting Win Probability Added closely follows runs scored per game. So, instead of listing the team leaders in batting WPA, I thought I'd present the following graph of runs scored per game compared to batting WPA. Teams above the line have had a bigger impact on games with their bats than their run totals would imply—vice versa for those below the line.

Poor Nationals. They not only have the worst offense in the majors, but the impact of their weak bats has been even lower than you would expect, given their output. Among other teams, the Cubs and the Padres have gotten relatively less win impact from their runs, while Tampa Bay has gotten the most (you can tell by estimating the gap between the team's place on the graph and the line).

Differences between runs scored and batting WPA usually can be ascribed to timing, or relative performance in high-leverage situations. That is, a team may rack up lots of runs in one-sided affairs, but fail to deliver with men on base in close games. That's an oversimplification, but you get the gist.

The player who has led Tampa Bay's relatively high batting WPA is Ty Wigginton, who is leading the majors in "clutch" (as calculated by Fangraphs). Clutch is a measure of how well a player has performed in high-leverage situations. Here is a list of the top 10 clutch batters in the majors.

Name             Team      RC    Clutch
Ty Wigginton     TB        12     1.29
Grady Sizemore   CLE       26     1.24
Troy Tulowitzki  COL       13     1.15
Placido Polanco  DET       24     1.00
Stephen Drew     ARI       16     0.86
Miguel Olivo     FLA       12     0.81
Prince Fielder   MIL       25     0.80
Adrian Gonzalez  SD        34     0.76
Victor Martinez  CLE       22     0.73
Luke Scott       HOU       15     0.71

You can see that Wigginton has created only 12 runs, but he has three of the top 32 WPA batting hits of the year so far, such as his single in the bottom of the ninth against the Twins on May 2 to tie the game (.436 WPA) and his home run in the bottom of the ninth against the A's on May 5 to win it (.430 WPA).

Grady Sizemore, by the way, may be batting "only" .255/.410/.445 (he's 16th in Runs Created), but he currently leads the majors in batting WPA, thanks to some timely hits. And do you think experience is necessary to be a clutch hitter? Well, youngsters Troy Tulowitzki and Stephen Drew, the two best hitters in the majors when leverage is above 3.0, might disagree with you.

Alex Rodriguez is having a great year. He smashed two of the top four WPA hits of the year on April 7 and 19, when his ninth-inning home runs won games for the Yankees (.750 and .720 WPA). In fact, he has been the third-best hitter in the majors when leverage is above 3.0. He is also second to Sizemore in major league batting WPA. However, his clutch score is only slightly above average (0.14).

Want to know why? Well, here's a look at how he's done in various leveraged situations:

Leverage Index    WPA
0-1              0.970
1-2              0.044
2-3              0.161
3-4             -0.171
6-7             -0.178
7-8             -0.200
8-9              0.746
10-11            0.718
Total            2.090

As you can see, A-Rod blasted his home runs in outrageously leveraged situations (LI doesn't go higher than 11) but he's been a negative performer in situations of middling leverage (3 to 8 LI). So, is A-Rod a clutch hitter or not this year? Let the debate begin! er... Again!

Bullpen WPA

Here's a list of each team's bullpen WPA and their Leverage Index, to date:

            WPA      LI
SD          3.88    1.25
LAN         3.39    1.09
MIL         2.86    1.19
BOS         2.74    1.04
STL         2.57    0.92
MIN         2.14    1.15
ATL         2.05    1.11
CHA         1.95    1.44
ARI         1.86    1.42
SEA         1.44    0.71
PIT         1.42    1.28
CLE         1.13    1.27
WAS         1.06    1.14
TEX         1.03    0.81
NYN         0.93    0.90
LAA         0.85    0.98
SF          0.74    1.05
DET         0.70    1.45
CHN         0.63    1.30
HOU         0.50    1.05
OAK         0.43    1.48
COL        -0.24    1.25
BAL        -0.48    1.08
PHI        -0.94    1.23
TB         -1.09    1.16
CIN        -1.29    1.03
NYA        -1.30    1.10
FLA        -1.72    1.56
TOR        -1.90    1.24
KC         -2.24    1.04

Win Probability Added is my preferred measure for bullpen effectiveness, and no bullpen has been better than San Diego's. They say that bullpens are hard to predict, but Kansas City has had just about the worst bullpen in the majors for as long as I can remember. And note that Florida's bullpen, which has the highest Leverage Index in the majors, has the third-worst WPA. They just haven't gotten the job done.

The Game of the Season, so far

I like to rate individual games by the total amount of WPA swings during the game. The more WPA changes, the more fans were on the edge of their seats. The most exciting game of April was Texas's 9-8 win over Toronto on April 28. The game was highlighted in THT Daily:

In one of the wilder games of the year, the Rangers prevailed over the Blue Jays, 9-8. The game featured several late-inning lead changes, thanks to Adam Lind’s two-run home run in the eighth (.273 WPA), Brad Wilkerson’s two-out, two-run single in the ninth (.588 WPA), Royce Clayton’s single in the ninth (.366 WPA) and Hank Blalock’s error-redeeming sacrifice fly in the 10th (.114 WPA).

Final Fact

The Mets, who have Jose Reyes, Carlos Beltran, David Wright and a bunch of fine hitters in their everyday lineup, are led in batting WPA by Damion Easley. In fact, he has the second-highest WPA on the team, trailing only John Maine.

That's because he had the fifth biggest hit of the year so far, a three-run homer in the top of the ninth against the Diamondbacks (.628 WPA). Just shows what one big hit early in the year can do for you.

Dave is the manager of the Baseball Graphs website.. Comments about this article can be sent to him through the miracle of e-mail.

Do you have a general question or comment for one of THT's writers? Send it in to our weekly mailbag We also welcome unsolicited op-ed pieces of approximately 500 words for consideration. We reserve the right to edit for length, clarity and consistency of style. Please include your whole name and location to be considered. If you have a comment about this specific article, please email the writer.

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