Are Catchers Brittle?

Eugene Freedman challenges the notion that catchers are more injury-prone than other position players:

Maybe you just believe all catchers are injury risks, but I disagree. I don't think they're any more a risk than any other skill position - second, short, centerfield, even third base.

Eugene's specific comment had to do with Joe Mauer, and was written at a point when Mauer's injury didn't seem as serious as it does now. But I'd rather address the more significant issue: are catchers riskier than other position players when it comes to playing time?

They weren't last year.

MLB Players with 400 or more Plate Appearances by Position

Pos	400+ PAs
C	20
1B	24
2B	26
3B	26
SS	26
LF	26
CF	29
RF	30

This surprised me a little bit. I would have expected fewer catchers based on my own perceptions and biases.

The evidence from last year backs up Eugene's point further. Only two major league catchers who were expected to garner significant playing time last year lost significant time due to injury: Victor Martinez and Jorge Posada. This is fairly comparable to most positions around the diamond, and there were more 3B in the A.L. alone who lost significant time due to injury (Hank Blalock, Eric Chavez, and Joe Crede).

Injuries or no, something I would expect from catchers would be diminished stats from the first half to the second half due to the wear and tear of the position.

Catchers -100 or greater in OPS from Pre All-Star to Post All-Star, 2008: Ryan Doumit (-.163), Russell Martin (.-123), Brian McCann (-.118), Brandon Inge (.-100).
-.050 to -.099: John Buck (-.093), Ivan Rodriguez (-.082), Dioner Navarro (-.067), Geovany Soto (-.064), Yadier Molina (-.063), A.J. Pierzynski (-.060), Jason Kendall (-.050).
+.049 to -.049: Joe Mauer (-.019), Chris Ianetta (-.004), Kurt Suzuki (+.019), Jason Varitek (+.047).
+.050 to +.099: Chris Snyder (+.050).
+.100 or higher: Bengie Molina (+.101), Ramon Hernandez (+.125), Kenji Johjima (+.165), Kelly Shoppach (+.200).

On the whole, there is a drop-off as the daily grind wears these players down. Eleven of the 20 catchers with 400 or more plate appearances in 2008 lost 50 points or more from their OPS from one half to the next while only five gained 50 points or more. However, there isn't a linear corollary where the catchers who had the most AB are all falling off the cliff as the season drags out. Martin's workload seemed to have a terrible impact on his offense down the stretch, but Mauer was unaffected. Age doesn't play a huge role, either. Anecdotal evidence would suggest that Pudge and Kendall are getting worn out with age and are withering as a result in the second half. B. Molina and Hernandez seem to challenge this concept.

I have to agree with Eugene and conclude that the current crop of catchers in the majors isn't necessarily an injury-prone bunch. There are a lot of other reasons why catchers aren't as good as other hitters for the purposes of Roto. The main reason they're not as valuable is because it is the one position left on the diamond where a Major League team might tolerate a 700 OPS in exchange for strong defense and steady pitch calling. But catchers, as a group, are no more injury prone than other players in baseball, and paying $24 for Joe Mauer in early February was no more of a risk than paying $42 for Alex Rodriguez at the same time would have been.