August 30, 2009

Catcher Fatigue

Effects on Batting Average?

by Tim Kniker

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During this year's All-Star Game, in the first inning as Joe Mauer came up to bat, and Tim McCarver wanted to emphasize to the viewers just how amazing Mauer's batting titles in 2006 and 2008 were, as well as his current production in 2009. McCarver said that one of the reasons that catchers don't win batting titles is because their batting average goes down late in the game with all of the bumps and bruises they get from donning the tools of ignorance. This seemed an interesting little theory from an ex-catcher that begged for some numbers to back it up. This comment also got me thinking about a potentially even larger issue: Does the wear and tear of playing at certain defensive positions on the field lead to reduced offensive production? Does this happens during the course of the game, and/or throughout the season?

In-Game Fatigue

I looked at the 2008 play-by-play data for Retrosheet to test McCarver's theory that catchers typically see their batting average fall toward the end of the game. Like most every position on the field, catchers actually see their batting average rise on the fourth or fifth time up in a game:

Times up in a game
Pos   PA 1-3   PA 4   PA 5+
C     .251    .269   .300
1B    .266    .273   .324
2B    .270    .274   .325
3B    .260    .272   .335
SS    .267    .264   .329
LF    .265    .265   .323
CF    .265    .259   .316
RF    .271    .279   .315

While all batting averages rise in the fifth time plate appearance (likely due to poor pitching by the opposition if the lineup is getting to bat a fifth time), the only two positions who saw their batting averages drop the fourth time up are shortstops and center fielders, the most active defenders in the field besides the catcher.

Now if we look at just the fifth plate appearance, the catcher does have the second-lowest increase (behind the right fielder) over their first three plate appearances. If we are thinking of batting titles, however, a fifth plate appearance occurs about two-fifths of the time that a fourth plate appearance does. (In 2008, there were a total of 31,811 fourth plate appearances, versus 13,074 fifth or greater plate appearances.) So let's combine the fourth and fifth plate appearances (and those rare occurrences beyond five plate appearances) into one statistic, and compare each position which is sorted in descending order.

     Times up in a game
Pos  PA 1-3   PA 4+   Difference
3B   .260     .289    +.028
C    .251     .276    +.025
2B   .270     .291    +.021
1B   .266     .286    +.020
RF   .271     .289    +.018
SS   .267     .284    +.017
LF   .265     .282    +.017
CF   .265     .277    +.012

If there's the case to be made for fatigue, it seems the center fielder has more of a reason to gripe, as he saw his batting average increase the least. Catchers had the second-highest increase in batting average, behind only the third basemen. However, is this just a one-year phenomenon? As a check, I also did the same analysis for 2006 and 2007, with the following results:

Late-Game Batting Average Increases
Pos    2006    2007    2008   Average
SS    +.033   +.031   +.017   +.027
C     +.024   +.029   +.025   +.026
3B    +.025   +.024   +.028   +.026
2B    +.028   +.018   +.021   +.022
LF    +.025   +.018   +.017   +.020
RF    +.011   +.024   +.018   +.018
1B    +.016   +.015   +.020   +.017
CF    +.014   +.015   +.012   +.014

Interestingly enough, in all three years, the center fielders are at or very near the bottom of the list, while catchers actually are at the top of the list in showing the most improvement in their batting average late in ballgame. Could the constant running required to patrol the outfield (since both the left fielder and right fielders are pretty low as well) take more of a toll within the game?

So what does this say about the original point, about Joe Mauer? Is he even better at staying at his level throughout the game, and is that is leading to the batting titles? It is interesting to note that his batting average was pretty consistent in his first three times up year-to-year, but in the one year he didn't win the batting title, he had a very low batting average in his late-game plate appearances. One thing to point out is that every in year, he typically performed worse in late-game plate appearances than he did in his early-game plate appearances, as compared to other catchers.

Joe Mauer's Batting Average in his Times Up
       PA 1-3   PA 4+   Difference
2006   .324     .351    +.027
2007   .317     .243    -.074
2008   .332     .333    +.001

Season Fatigue

So there seems to be no evidence of catcher fatigue during a game hurting their batting averages. However, couldn't the constant beatings that they take throughout the year take its toll? For all players who had at least 400 plate appearances at a single position, I compared their batting averages in their first 300 plate appearances to their batting averages from plate appearance 301 and above.

Season Plate Appearances
Pos  1-300   301+   Difference
C    .292    .268    -.024
1B   .270    .285    +.015
2B   .279    .290    +.011
3B   .273    .271    -.002
SS   .273    .291    +.018
LF   .283    .290    +.007
CF   .270    .270     .000
RF   .288    .286    -.002

So an initial look at 2008 suggests that maybe catchers do wear out as the season progresses. However, if we increase our scope and go back to 2006, we see that this just happened to be a one-year occurrence:

Batting Average Difference Between First 300 PA and 300+ PA
Pos    2006     2007     2008
C     -.004    +.011    -.024
1B    +.005    -.001    +.015
2B    -.001    +.001    +.011
3B    -.003    +.021    -.002
SS    +.014    +.006    +.018
LF    -.003    -.003    +.007
CF    +.001    -.004     .000
RF    -.018    +.008    -.002

When we see the three years in perspective, the data suggest that there isn't really a significant impact on catcher performance in terms of batting average during the latter portion of the long regular season. Perhaps the likely cause is that any fatigue that might occur with any one position's performance at the plate is likely to be equaled by pitcher fatigue, such that it all evens out in the end.

Tim Kniker is a conributor to Baseball Prospectus.

Tim Kniker is an author of Baseball Prospectus. 
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