I was randomly perusing the pitch type data on FanGraphs today looking for the pitcher who throws the hardest average slider (Justin Verlander at 87.9 mph, although he only throws it 2.3% of the time). This led me to do some sorting by pitch type percentage to see who the leaders were in terms of how often they throw a certain type of pitch. I'm not going to try to get into heavy analysis here, but I thought the results were somewhat interesting.
Fastball: Mike Pelfrey, 78.3%. Not exactly sure what to say about this, but Pelfrey's definitely not a strikeout artist at only 5.22 K/9. He does actually throw his fastball a little harder on average than I would have expected, however, at an average of 92.6 mph.
Curveball: Wandy Rodriguez, 36.8%. Rodriguez is actually significantly ahead of second place in this category (A.J. Burnett at 31.1%). His curve averages 77 mph, and apparently the frequency at with he throws it helps to keep hitters off-balance, as evidenced by his 8.45 K/9 last season.
Cutter: Doug Davis, 45.5%. Davis uses the cut fastball as his primary pitch, with an average velocity of 82.6 mph. Hardly what you'd call a fireballer, but Davis has managed to be at least a moderately effective back-of-the-rotation innings-eater type, a role he'll resume in the Milwaukee rotation in 2010.
Slider: Ryan Dempster, 34.2%. Dempster features both a slider and a splitter, but throws the slider much more often as the alternative to his fastball. He was actually the bright spot of the Cubs' rotation last year, logging 200 IP with a 3.65 ERA and 7.74 K/9.
Changeup: Johan Santana, 31.0%. No surprise here; Santana's changeup is the filthiest in the game and he uses it to great effect. Brings me back to the good old days when I'd watch the befuddled look on the faces of Twins' opponents after having watched the bottom drop completely out of the pitch they just whiffed at.
Splitter: Braden Looper, 34.1%. There aren't a ton of pitchers that feature a splitter (other good examples are Carlos Zambrano and Dan Haren) but Looper throws it way more than anyone else. He led the league in 08' at 18.4%, and in 09' he nearly doubled the frequency at which he throws it. For featuring a splitter, however, I was surprise that Looper's ground ball rate was only 46.4% last season.
Kuckleball: Tim Wakefield, 84.9%. Duh.