Figure 1: Two graphs showing the Velocity, Horizontal Movement, and Vertical Movement (not counting the drop due to gravity) of Mike Pelfrey's pitches on opening day. The pitches are organized by color:
Red = Four-Seam Fastballs
Orange = Two-Seam Fastballs/Sinkers
Yellow = Splitters
Blue = Sliders
Purple = Curveballs.
NOTE: I'm really not confident in my breakdown of 4-seam and 2-seam fastballs; Harry Pavlidis came up with different groupings. But those ARE fastballs of some type.
So in honor of opening day I opted to take a really quick look at Mike Pelfrey's pitches from today using pitchf/x. The pitches can be seen above in Figure 1.
One interesting thing of note was Pelfrey's low use of his splitter in this start. If you recall, Pelfrey started big on that splitter last year, but decreased his usage of the pitch as the season went on. By September, he would still use the pitch 18% of the time against left-hand batters (down from 25% to start the season), but only 8% of the time against right-handed batters (down from a high of 22.5% of the time in June).
Today, Pelfrey threw 3 splitters to left-handed batters out of 34 pitches (8.8%) and 5 to right-handed batters out of 63 pitches (7.9%). Mind you this is a ridiculously small sample size, but clearly Pelfrey wasn't looking to use this pitch as he did to start last year, as a new deadly weapon.
The pitch's movement and velocity by the way seem basically the same as last year, as much as we can tell from this tiny sample (8 pitches).
The other clearly interesting thing about this game was Pelfrey's use of his slider. At the end of last year, Pelfrey increased his usage of his slider against right-handed batters dramatically (at the same time as his splitter use was dropping). He went from throwing the pitch against these batters 6.6% of the time in June to 22.7% of the time in September. By Contrast, Pelfrey barely used the pitch against left-handed batters (those batters faced the curveball instead)
Pelfrey continued these trends on opening day. He threw sliders to right-handed batters 1/3 of the time (21 out of 63 pitches)! Of course....this wasn't an amazingly successful tactic: While the pitch did result in 4 outs and a swinging strike, 12 of these 21 pitches were called balls. Of course, all 4 of these outs were groundouts, so it's not like the pitch was poor either.
Really nothing else is worth noting about this start based on the data we have here. Pelfrey threw 8 curveballs, all to left-handed batters (a trend continuing from last year), but mainly relied upon his fastball against both types of batters. Obviously, he did not have great results.
Pelfrey's pitches appear to be the same in movement and velocity as last year. The question is whether he can harness them better. He seems to be continuing his trend from September in ditching the splitter largely and relying upon his slider as a prime off speed pitch. I'm not quite so sure that's the best option for him.
One thing I haven't touched on his the ground ball rate on these pitches, mainly because we can't really judge that based upon one start. But it bears major watching. Last year (as you'd know if you read the Amazin Avenue Annual), Pelfrey could get ground balls from Righties, but against lefties the ball was quite frequently in the air. As Pelfrey pitches throughout this month, we need to keep an eye on whether that trend continues.