THE BOOK--Playing The Percentages In Baseball

Sunday, September 25, 2011

WOWY and catcher framing

I used Mike Fast’s list of the best and worst framing catchers from 2007-2010 and did a WOWY between them and all the starting pitchers they caught in that time period. If you have not read Mike’s recent article on quantifying catcher framing using pitch f/x data, you should.

Anyway, I compared the wOBA against, NIBB, and SO rates of all the starting pitchers (when they started) matched up with each of the catchers in my sample and those same starting pitchers when they pitched (again, only as a starter) with another catcher (regardless of the team).  I weighted each of the differences by the lesser of the two PA and summed and averaged all the data (the weighted differences) for two groups - the 10 best framing catchers and the 10 worst, using regressed (adding 60 games of league average framing) runs per 120 games.

The 10 best (at framing, per Mike Fast) were

Alex Avila
Hanigan
Lucroy
Russell Martin
Jose Molina
Montero
Ross
Saltamacchia
Torrealba
Zaun

The 10 worst were:

Doumit
Hill
Hundley
Ianneta
Johjima
Rob Johnson
Kendall
Laird
Posada
Treanor

Here is an example of the methodology:

Say there are 2 catchers in the good group, A and B.

And say that A caught pitchers I and J, and B caught pitchers X and Y.

Say that pitchers I and J had a wOBA against of .300 and .310 with catcher A behind the plate and .290 and .306 with all other catchers behind the plate.

And say that the number of PA for pitcher I with catcher A was 100 and for pitcher I and all other catchers it was 300.  The difference in wOBA is .300-.290, or .010, weighted by 100 (the lesser of the two PA).

For pitcher B, the difference is .310 - .306 or .004, weighted by the lesser of those two PA, say, 150.

We do the same thing for catcher J.

We take the weighted average of all the wOBA differences.

I did the same thing for BB and K rates (per PA).

We would expect that the good framing catchers would have a better wOBA with their pitchers than with those same pitchers and another catcher.  We also expect them to have a better K rate (higher) and BB rate (lower).  Vice versa for the bad framing catchers of course.

Keep in mind that I did not control for anything else which might effect the offensive environment, such as park, weather, strength of the offensive opponents, etc. Also keep in mind that any WOWY differences found would include pitch calling skill by the catcher.

Anyway, here are the results:

Higher wOBA by 2 points, which is around .07 runs per 9 innings.  Lower K rate by .23 K per 9 innings.  Higher BB rate by .19 per 9.

Obviously there is some noise in these numbers.  I don’t know the standard error off the top of my head.  The total number of PA for each group for purposes of weighting (IOW, summing all the “lesser of the PA") is around 50,000, which is a lot.  There also may be biases, as I said, caused by different parks, opponent offenses, weather, etc. in the withs and withouts. 

Again, these numbers include pitch calling.  In fact, one reason why the bad framing catchers only had 2 points of wOBA worse may be that they are superior pitch callers otherwise they would not be catching given their poor framing skills.

I did the same test using out of sample data - 2003-2006 - for the same catchers.  Obviously some of these catchers had little or no playing time in those years.  Here are the results for them for this time period, 03-06.  If what Mike is capturing is indeed a “skill,” (and his y-t-y correlations suggest that it is a strong skill) we should see similar results in the out of sample data.  Indeed we do!

Good framers

Higher wOBA by a whopping 14 points, which is around .46 runs per 9 innings!  Lower K rate by .46 K per 9 innings.  Higher BB rate by .15 per 9.

Here there is no evidence that the bad framers are good game callers.  Just that they are terrible catchers overall!