In yesterday’s One Night Only Carson Cistulli observed that Matt Garza is throwing his two-seam fastball, slider, and changeup about twice as often this year as previously — making him entirely different pitcher. Pitch F/x-guru and Cubs-fan Harry Pavlidis, with his own reclassifications of the Pitch F/x data, came to Carson’s aid and found that Garza is indeed throwing more sliders and changeups, but not any more two-seam fastballs. There are improvements in the Pitch F/x’s internal classification system during the offseason and that is probably responsible for the shift Carson saw in two-seam fastball frequency.
All those changeups and sliders are coming at the expense of Garza’s fastballs. During his three years with the Tampa Bay Rays Garza threw about 71% fastballs, over that time his fastball percentage was fourth highest among starting pitchers. This year his 53% fastball use is solidly below average among starting pitchers. That is a fairly dramatic shift.
I wanted to see whether this shift was just start-to-start fluctuation and whether Garza had gone through a run of starts in 2010 when he threw this few fastballs. I also reclassified all of Garza’s pitches from the Pitch F/x data. To the right is a graph of Garza’s secondary pitch fraction by start using the FanGraphs Pitch F/x color scheme: orange for changeups, red for sliders, and purple for curves. In each of his last four starts Garza has thrown over 40% non-fastballs. In all of 2010 he did that just three times. So it definitely looks like Garza has dramatically shifted his pitch breakdown, throwing many fewer fastballs.
Garza is pitching ridiculously well so far in 2011 — his 1.93 xFIP leads the league — though he has been very unlucky. Like all early season outliers a huge part of this is just the small sample size. But if I had to guess I would say that fewer fastballs makes Garza a better pitcher. Most pitchers who throw upwards of 70% fastballs are ground-ball pitchers throwing mostly a two-seam fastball. Garza doesn’t fit that profile, so I think these additional sliders and change ups make a lot of sense for him.