Clay Buchholz is a bit of an enigma. He's a guy who pitches a no-hitter last year and has, supposedly, incredible stuff... at the same time he can't seem to put it together to get out Major League hitters.

Over his last few starts, he's been shelled. In the 5 starts before the one this afternoon, he gave up 5 HR and was good for a 6.59 ERA, with 15BB and only 24K. Today, he gave up 3 more HR, 5 more runs, and 7 hits - all in 3 innings pitched.

What's working for Clay, and what's not? To answer this question, we'll turn to a specific PitchFX plot from his most recent start.

An interesting feature of Clay's changeup is that it doesn't move the same as the change that's normally seen in the majors. Most changeups fade away from LHH (or in to RHH). This makes them fairly easy to identify on a Horizontal Movement X Speed plot because they usually lie opposite of the Curveball. Clay's pitches are a bit more difficult to identify using only horizontal movement because his changeup fades in the other direction. This also leads to the Gameday system (and, somewhat amusingly, the Fenway Park scoreboard) to call most of his changeups as sliders:



You can see it's difficult to tell apart his offspeed pitches which all cluster in the righthand side of the graph.

On the other hand, it's easy to tell them apart if we plot Speed x Spin Direction Angle. We can calculate the spin direction by using a formula from Alan Nathan to recreate the way the ball was spinning on its way to the plate (which subsequently results in most of the movement on the ball):



There. That's easier. On the plot above, there are 4 distinct pitches: the fastball (green halo), the changeup (red), the slider (blue), and the curveball (orange). You can see by looking at the individual dots that most of the hits (light blue) come on the fastball and the curveball. If you watched the game, it was pretty clear that his fastball command was bad and hitters were really teeing off on it.

On the other hand, look at the changeup (red). 13 changeups. 12 strikes, 7 swinging. And only 1 ball. That's basically as effective as an offspeed pitch is possibly going to be in a single game. Hitters had no idea what to do with it.

It's pretty hard to argue with the results when your pitcher is getting lit up and he can't command his fastball. But he still has that dominant pitch.

The strange thing about this dominant pitch is that while it was leaned on very heavily early in the season, he has stopped throwing it as much as he once was. At his start in Tampa on 4/26, where he went 9 innings (eventually taking the loss on a 2-run bomb), he threw 40 changeups in 113 pitches.

It's just as dominant then as it was today, but then it was 35% of his pitches:


Today, he threw 13 changeups in 74 pitches, which is 17.5% - or exactly half of what he used in the dominant start at Tampa. Admittedly, part of this is probably dictated by the fact that he was pulled early in the game, but through his first 74 pitches at Tampa he had 33 changeups - a 45% clip. On 8/4 he threw 15 changeups in 93 pitches. At LAA he threw 18 in 90. At Tampa he threw 41 through 113.

Every time you don't call for the changeup, you're replacing a great pitch with a mediocre fastball. And since his return, he's been much more fastball-heavy, even though his changeup hasn't lost any of it's effectiveness.

Is the Clay we saw today the same pitcher as early in the season at Tampa or last year during the No-no? Perhaps not. The Tampa start might have been a fluke. Or, we could be seeing the result of strange game planning, pitch selection, and bad execution from Varitek and Buchholz. For whatever reason, he's gone away from the dominant changeup, and it isn't working.