Another straight, effective fastball

If you don’t know him already, you should try and learn a thing or two about Mark DiFelice. In a nutshell, he’s a reliever for the Brewers who, after a long career in various levels of the minor leagues, has been mowing down hitters with nothing but an 82-mph fastball. No knuckleball or gyroball or anything like that, just batting practice fastballs that make guys like Hanley Ramirez look foolish.

In a post at FanGraphs, Dave Cameron presents this pitch f/x graph from one of DiFelice’s games:

Gameday classifies those pitches as sliders and changeups because, well, major league pitchers just don’t throw nothing but fastballs at 82 miles per hour and get away with it. DiFelice isn’t just getting away with it, he’s been more than 2 linear weights (LW) runs above average per 100 pitches with it despite throwing it almost every single time. The average horizontal movement of that “thing” is between +1.4 and -2.9 inches, so it’s pretty straight. But part of what makes it effective is that, compared to the average major league fastball, it’s not straight at all. Major leaguers have fastballs that, on average, tail about 5 inches to the arm side. Don’t believe me that it’s a fastball, DiFelice says so himself in that Yahoo link above.

I’m not going to go further in analyzing DiFelice, because my pitch f/x abilities are severely limited in that regard, and Dave Cameron already did a good job of it. What I noticed today was that there is another mostly unknown pitcher who has a similarly puzzling fastball.

That pitcher is David Robertson, a reliever for the Yankees. Robertson was known in the Yankees system as a guy with a devastating curveball and an average fastball. Radar guns confirmed this in the major leagues, when people saw the 90-91 mph fastball and his big looping curve racking up the strikeouts. I checked out his player card today and was surprised to see that 80% of his pitches this season have been fastballs. Not only that, his fastballs are registering 1.47 LW runs above average per 100 pitches. That puts him in the same company as Jonathan Broxton. Take another look at that graph above for DiFelice, and then look at this graph for Robertson’s game on June 12th against the Mets:

Ignoring the colors, look at the cluster of dots in the middle of the graph. Yes, I realize that DiFelice’s ball drops a lot more than Robertson’s, but the horizontal movement is almost exactly the same. Robertson’s fastball is more like a cutter than anything else, and that’s probably why it has been so effective at around 90 mph, despite throwing it 4 out of every 5 pitches.

Ask any Yankee fan how Robertson has been able to have a strikeout rate of over 13 per 9 innings this year and over 11 per 9 innings in his career, and he’ll probably tell you it’s because of that curveball. And it might be because of it–after all, that huge curve might be in the back of a hitter’s mind, causing him to miss the fastball. If you want to surprise him, tell him just how effective Robertson’s “just average” fastball has been, and you’ll end up looking real smart.


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