Matchups Revisited

By Bill

In 792 career plate appearances in August, Rusty "The Red Baron" Greer hit an impressive .353/.431/.579. In months other than August, Greer hit a solid but much less striking .294/.377/.456. In no other month did he hit below .289 or above .297, and in no other month did he hit more than 20 career home runs (he hit 32 in Augusts). Greer even went 9-for-9 in steals in August, and was a putrid 22-for-37 in other months. Is that enough to conclude that Rusty Greer was just really good at playing baseball in August?

The Common Man wrote a very, very good piece on Thursday in which he looked at pitcher-batter matchups for the top 60 pitchers by innings pitched since 1950. The results, while very interesting, were unsurprising; they were all over the map. When you're just looking for a very large number of plate appearances against one pitcher, you're looking almost exclusively at very-good-to-great hitters against very-good-to-great pitchers, and of course you're going to see some hitters who did very well against a certain pitcher, some who did poorly, and others (most of them) who did exactly what one would expect, i.e., slightly less well against that very good pitcher than they did overall.

It's all great stuff. TCM notes that even the most frequent matchup he could find -- Pete Rose against Phil Niekro, which happened 266 times -- is equivalent to only about 60 full games. He then points out that through about that many plate appearances to start 2010, Brennan Boesch looked like a superstar, but then finished out the year looking very much like the AAA player he actually is (well, no, he looked even worse than that).

All of which makes his conclusion something more than puzzling: explaining away the Boesch example by claiming that matchup stats are "less prone to streaky runs" than stats from continuous stretches, and then that fluky streaks are less likely with matchup stats because hitters and pitchers know each other better, TCM draws the following guess conclusion:

So where’s the line? TCM is tempted to put the number around 150, though obviously 200 is even more instructive. The trouble, as you can see above, is that players are increasingly unlikely to hit that mark in today’s game, making Hitter vs. Pitcher data little more than a fun exercise.

Well, that last part is certainly true. The venerable Derek Jeter hasn't faced a single pitcher 150 times, and isn't likely to see that many more chances against his number one, the even more venerable Tim Wakefield (currently 127). With 30 teams, interleague play and a great deal of player movement from year to year, this isn't just something that's going to be useful going forward.

What I'm stuck on, though, is landing on a number like 150 or 200. That seems crazily low to me, and I don't think it's supported by anything TCM wrote.

Matchmaker, Matchmaker, Make Me a Match

By The Common Man

There has been a lot of snark, in the wake of the Yankees' loss in the ALCS, about Joe Girardi and his little binder of pitcher-hitter matchup data (the use of which, as Craig Aaron points out, is in no way sabermetric).  On Tuesday, in his chat on ESPN, Rob Neyer stirred up a sample size hornets nest when he took a question from John in NYC:

John (New York, NY): Rob, the sample size of batter/pitcher matchups is of particular interest to me. Obviously a sample size of 5-10 PAs against a single pitcher does not yield any useful data. However, when you consider that in those 5-10 PAs, a single batter is only facing the repertoire of a single pitcher, my question is how many PAs are required before the data becomes significant? 20? 50? More? What do you think?

Rob Neyer: More than 20. I'm not sure if 50's enough. I'm not sure if any batter has ever faced a pitcher enough times to show us anything truly meaningful. I think what makes more sense is looking at how a hitter has fared against *types* of pitchers.

Later, another New Yorker had a follow up:

Jeff (NY): While I agree that 0-20 from one batter against one pitcher is too small of a sample size, aren't the odds higher that the batter will continue to struggle than if he were 0-2? I don't think varying degrees of samples, with regards to educated predictions, is talked about enough. For example, 0-5 is meaningless, 0-10 is less meaningless, etc. Does this make any sense? Is there any research I can read on it?


Rob Neyer: I don't know of any research, but yes I would assume you're correct: 0-20 is more useful than 0-2. The question is whether or not 0-20 is useful enough to use.

This piqued The Common Man’s curiousity, and he did some digging through Baseball Reference’s Play Index function to see just how much exposure a batter could get to a pitcher. First, though, a couple notes.

1. The Play Index only has play-by-play data as far back as 1950, so all figures are from 1950-2010. This means that a few of the pitchers TCM looked at here (such as Warren Spahn, Robin Roberts, and Billy Pierce) have incomplete data.
2. Second, TCM limited his examination to the Top 60 pitchers (measured by Innings Pitched) of the last 60 years. This is convenient for a number of reasons. For one thing, it limits the pool to a manageable size. For another, there are exactly 60 pitchers who have, since 1950, thrown more than 3000 innings in the Major Leagues. And finally, the opportunity for pitchers with fewer than 3000 innings to face a batter enough times to be significant is incredibly low.
3. And third, TCM listed all batters who had more than 150 plate appearances against these pitchers, as well as a few select matchups that occurred 100-150 times that were particularly interesting.