Tuesday, December 28, 2010

Catcher Defense - Part 2

In an earlier post, I touched upon the difficulty of measuring pitcher handling by catchers.  Numerous Studies have been done regarding this issue, but none have shown conclusively that pitcher handling is a skill that can be repeated from one year to the next.  This is perplexing because so many people inside the game insist that pitcher handling is very important and that some catchers are significantly better at it than others. One possible solution is John Dewan's catcher earned run saved statistic described in my previous post.  However, that measure is a work in progress and is limited by small sample sizes for pitcher/catcher duos.

Other catcher duties are easier to quantify than pitcher handling because they are somewhat independent of pitchers.  This includes throwing out base runners, preventing passed balls and wild pitches and avoiding throwing and fielding errors.  Pitchers do have some influence over these rates.  For example, a catcher who frequently catches a knuckleball pitcher will probably have a high number of wild pitches and passed balls. 

Also, since left-handed pitchers are typically better at holding baserunners than right-handed pitchers, a backstop catching a heavily left-handed staff will tend to have better success preventing steals.  Still, the relative frequencies of stolen bases, caught stealing, wild pitches, passed balls and errors tend to be fairly consistent from year to year for many catchers, suggesting that these measures probably represent real skills.

Two statistics that measure the ability of catchers to control the running game are stolen bases attempted per nine innings (SBA/9) and caught stealing percentage (CS%).  Victor Martinez had a 1.25 SBA/9 catching for the Red Sox last year.  This means that, base runners attempted to steal 1.25 bases per full game when Martinez was catching.  That was substantially worse than the league median of 0.80  The only catcher who was worse was Jason Kendall of the Royals (1.26).The best was Rod Barajas (0.46) who split time with the Mets and Dodgers. 

Martinez had a CS% of 21% meaning that he threw out 21 percent of base runners attempting to steal.  This was less than the MLB median of 29%, but he was far from the worst.   Chris Snyder of the Diamondbacks and Pirates threw out only 9%.  The Cardinals' Yadier Molina was the best at 49%.

Pitch blocking can be measured by wild pitches and passed balls per nine innings (WPPB/9).  Wild pitches are included in the calculation, as it is often difficult to distinguish between wild pitches and passed balls and it is possible that official scorers give some catchers or pitchers the benefit of the doubt based on reputation. 

Martinez's 0.41 WPPB/9 was right at the MLB median.  Phillies catcher Carlos Ruiz was the best (0.16) and Angels backstop Jeff Mathis (0.73) was the worst. 

Finally throwing errors per nine innings (TE/9) and fielding errors (FE/9) per nine innings are used to measure error prevention by catchers.  Martinez had .05 TE/9 and 0.01 FE/9, which was close to the MLB median in both cases.  Catcher errors are infrequent and some made no throwing errors or no fielding errors.  Russell Martin of the Dodgers had the worst TE/9 (0.10) and Adam Moore of the Marlins the worst FE/9 (0.05). 

How did Alex Avila rank?

SBA/9 = 0.75 (slightly better than the median)
CS% = 32% (slightly better than median)
WPPB/9 = 0.56 (worse than median)
TE/9 = 0.02 (better than median)
FE9 = 0.01 (better than median)

In a future post, I will combine all of the above metrics into one number representing a catchers overall performance beyond the elusive pitch handling skill.

The raw data for this article were abstracted from Baseball-Reference.com.

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