Friday, August 23, 2013

Washington Post Sports Watch: Boswell's Statistics Don't Quite Add Up

Tom Boswell wrote a really interesting column the other day about baseball catchers and the importance of pitch selection, or  "calling the game." Part of the piece talked about how pitch selection is somewhat of a dark art -- no one really talks about what might make one catcher better than another -- and it noted that in many cases, there may not be one "right pitch" to call for, but there is probably is a "wrong pitch." The bottom line of Boswell's column was that Wilson Ramos might be particularly valuable to the Nats because, according to the statistics Boswell cited, he's really good at "calling a game." But as I read the column, one big problem stood out: While Boz's argues that Wilson Ramos could be an elite pitch caller, the statistics he cite don't actually prove that --they merely demonstrate that Ramos is a better pitch caller than Kurt Suzuki.

Boswell uses catcher ERA as his statistic to measure a catcher's proficiency in calling a game, and that's fine. But because catcher ERA is a statistic that is so dependent on the quality of pitchers the catcher is catching, it's virtually impossible to use that statistic to compare a catcher from one team to a catcher on another team. For instance, the catchers on the 2006 Nats could have been the greatest pitch callers in the major leagues -- they still would have had a pretty high catcher ERA because that pitching staff was so lackluster. So when Boswell notes that Ramos has a 3.30 catcher ERA this year, while Kurt Suzuki has a 3.96 ERA, they tell us that Ramos is better behind the plate than Suzuki, but it is meaningless in telling us how either of them stack up with other MLB catchers --  neither of those ERAs can be compared to any other catcher in baseball this year because those other catchers are dealing with completely different pitching staffs. So in order to prove Boswell's point that Ramos is not just better than Suzuki, but could be better than many other catchers in the majors in pitch selection, we have to find other catchers who have worked with the same pitching staffs that Ramos and Suzuki have.

(And by the way, there's a huge caveat with all these numbers -- a pretty small sample size. Wilson Ramos has only caught 71 games in the last two years, less than half a season, and just 46 this year. But that's what we've got, and that's what Boz is using to make his point, so that's what I am going to use as well to poke holes in Boz's argument.)

So let's go back to 2012, when Jesus Flores actually caught more games for the Nats than either Ramos or Suzuki. Flores' catcher ERA was 3.36, Suzuki 3.46 and Ramos a very low 3.07. So based on those numbers, Boz might be right--although considering Ramos caught a very small sample size of just 24 games that year, I wouldn't really use these statistics to prove much of anything. So let's go to Oakland, where Suzuki played the bulk of the year in 2012. Suzuki had a 3.52 catcher ERA in 75 games, while Derek Norris (a former Nats prospect!) had a 3.08 ERA in 60 games. Based on those numbers, Derek Norris might be a really good pitch caller ... or perhaps Suzuki just isn't a good pitch caller. He's now trailed both Ramos and Norris by at least a half run the past two seasons We really don't know.

So let's take a couple more stats Boz provides us--catcher ERA using history catching particular pitchers. Suzuki has a 3.66 ERA in 101 starts catching Gio Gonzalez. Considering Gonzalez has a 3.60 career ERA, that would indicate that Suzuki is a pretty average catcher. But then there's Dan Haren--who has a 5.25 ERA when caught by Suzuki (including a number of starts when Haren was in Oakland and "younger and better," to quote Boz.) and a 3.72 career ERA. That, of course, seems to indicate that Suzuki perhaps is a below average catcher.

I could go on, but you probably get the point. These statistics appear to tell us that Ramos probably is better than Suzuki behind the plate, but it's entirely unclear whether that's because Ramos is above average or Suzuki is below average (or, perhaps, both!) So while Boswell's optimism is nice about Ramos--that he can truly be a difference-maker with pitchers--his evidence he presents for such a contention is, right now, fairly slim.


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