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May 10, 2000

Catcher Career Paths

Do They Peak Later?

by Keith Woolner

There's a commonly held belief in sabermetric circles that catchers reach their offensive peak later that players at other positions. Presumably, the physical strain of playing catcher inhibits their development as hitters. The emergence of Darren Daulton at age 30 is typical of this phenomenon. However, to the best of my knowledge, there has not been a study to back up that intuition.

I decided at look at the issue in more depth, using the free player statistic database at http://www.baseball1.com. I did two different studies, looking for evidence that catchers peak later than players in general.

Study 1

For the first study, I computed the aggregate RC/27 for all catchers who had 300+ PA at a certain age, and looked at the total performance of those players the following year, provided that they still played catcher most frequently and amassed 300+ PA. I then looked at the ratio between the aggregate RC/27s, and compared it to a prior study that did the same thing for all players.

Numbers above 1.000 indicate that the group as a whole improved the following year, while numbers below that indicate that the group as a whole declined the following year. I've included only ages that had at least 10 qualifying catchers (all but age 21 had 20+ data points).

      Catcher   AllPlayers
Age    Ratio       Ratio
21     1.057       1.112
22     0.974       1.059
23     0.977       1.031
24     1.065       1.015
25     0.988       1.024
26     0.982       0.999
27     0.988       0.985
28     0.988       0.987
29     0.970       0.983
30     1.002       0.976
31     0.912       0.970
32     0.969       0.973
33     1.014       0.970
34     0.914       0.946
35     0.886       0.947

The study does not show a clear trend that would indicate a later peak for catchers. Very young catchers seem to wear down slightly while other position players are improving. Catchers hold their value pretty well during their late 20s, comparable to other positions. The 30 to 33 range is very volatile, with ratios jumping all around, but the average for the period is .974, comparable to the all-player average of .972, so the decline is about as quick. After age 34, things go downhill very quickly for catchers, a trend noticeable even in the very small sample sizes beyond age 35 that aren't shown here.

Study 2

For the next study, I looked at the age at which the player had his season with the highest total contribution. Several years ago, I had previously done a study with Adjusted Batting Runs for all players (available at http://www.stathead.com/bbeng/woolner/peakage.htm). The Baseball1 database did not have ABR available, so for the catchers' portion of the study, I used a comparable measure called Marginal Runs Created (MRC), defined as:

OUTS*(RC/Out - LgRC/Out), where RC/Out = OBP*SLG/(1-AVG)

but not adjusted for park. I looked only at players who had 10 seasons with 100+ PA and with catcher as their primary position. I computed the age they had their highest MRC total, and took that as their peak season (players who reached identical peak totals in two different seasons are credited with two peak seasons). I then counted how many catchers peaked at each age, and compared it to the results from my previous study.

           Catchers                 All Players
Age   Num   Peak%   Cumul%      Num   Peak%   Cumul%
21      1    0.8%     0.8%       29    1.8%     3.2%
22      6    4.7%     5.4%       55    3.5%     6.7%
23      5    3.9%     9.3        87    5.5%    12.2%
24      7    5.4%    14.7%       90    5.7%    17.9%
25     14   10.9%    25.6%      148    9.4%    27.2%
26     12    9.3%    34.9%      160   10.1%    37.4%
27     15   11.6%    46.5%      163   10.3%    47.7%
28     13   10.1%    56.6%      155    9.8%    57.5%
29     11    8.5%    65.1%      138    8.7%    66.2%
30     12    9.3%    74.4%      141    8.9%    75.2%
31     12    9.3%    83.7%      107    6.8%    82.0%
32      5    3.9%    87.6%       91    5.8%    87.7%
33      3    2.3%    89.9%       68    4.3%    92.0%
34      7    5.4%    95.3%       46    2.9%    94.9%
35      1    0.8%    96.1%       25    1.6%    96.5%
36      2    1.6%    97.7%       22    1.4%    97.9%
37      1    0.8%    98.4%       13    0.8%    98.7%
38      2    1.6%   100.0%        9    0.6%    99.3%

As with position players, the most frequent peak age for catchers is 27. The peak range for catchers extends from 25 to 31, with a strong dropoff on either side. The dropoff for all players ends a year earlier at age 30, so there is some credence to the idea that catchers can still reach their peak around age 30-31 more often than players who play other positions.

The "Cumul%" column measures what percentage of players have seen their peak season by a certain age. Fewer catchers of a given age have peaked than comparable position players at every age until age 31, though the differences are small. Given that we are looking at an aggregate measure of value, rather than a rate measure, a managerial bias towards giving veteran catchers more playing time could be enough to tip the percentages slightly towards the older catchers as we observed.

Conclusion

Catchers do not improve or maintain their rates of production into their late 20's or early 30's. There's only the slightest tendency for catchers to have their peak season at ages 30 and 31 more often than other position players.

Overall, I don't view the evidence as a strong trend for a later offensive peak. Perhaps we should abandon the idea of catchers developing more slowly, and recognize that the physical demands of the position will tend to reduce both the length of their peaks and the length of their careers.

Keith Woolner is an author of Baseball Prospectus. 
Click here to see Keith's other articles. You can contact Keith by clicking here

Related Content:  Catchers,  Peak Age

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