EDIT: The following post was based on incorrect data and faulty reasoning on my part. Unless you pretend Jimenez is throwing a whiffle ball, the the fastball’s pitch trajectory is physically impossible. You can read a full retraction here.
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I think we all realize that “rising” fastballs don’t actually rise. They just drop less than a pitch without as much backspin. If you want conclusive proof, there’s a great Mythbusters that investigates a number of baseball myths, including the rising fastball. Roger Clemens even makes an appearance.
That being said, take a look at the red fastball thrown by Ubaldo Jimenez below. (Courtesy of another fine PITCH f/x article by Dan Fox.) The path of the pitch flattens out as it approaches home plate. (I held a piece of paper to my screen to make sure.)
Viewed from the side, the green slider is more or less a neutral, “non-rising” fastball — it contains mostly side-spin and thus little top- or back-spin.
I always assumed every pitch trajectory was a downward-facing parabola, like the slider, and that a fastball was just the most flat. But the trajectory of this fastball is concave up! From high school calculus, that means the second derivative is positive. In English, the pitched ball is accelerating upwards. If the force created by the spin perfectly matched the force of gravity, the ball would travel in a straight line. This fastball rises above the straight line path that Jimenez originally released it on. And that is why they call it a rising fastball.
(As an aside, I can’t imagine how difficult it is to differentiate between the red fastball and the green slider as a hitter. They start out on the same path, but then one “rises” and moves slightly to the catcher’s left while the other falls and curves significantly right. At 95 mph. Nasty.)
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Sky is a baseball fan and racket sport afficianado living in upstate NY. His favorite color is orange and is just about ready to give up on his life-long dream to become the next Magnus ver Magnuson (World's Strongest Man). His favorite baseball teams are the Yankees and Red Sox, proving that there's hope in the Middle East.
August 29th, 2007 at 2:08 pm
Sky, there must be something deceptive in Dan’s graph of that fastball, because the acceleration of the pitch is still positive (toward the ground) according to the Gameday data:
http://gd2.mlb.com/components/game/mlb/year_2007/month_08/day_25/gid_2007_08_25_wasmlb_colmlb_1/inning/inning_1.xml
It lists az=”-18.704″ for that 99.6-mph pitch to Dmitri Young in the first inning. The az would need a magnitude greater than that of gravity, 32.174, in order to be accelerating away from the ground to produce a concave-up trajectory.
Maybe it’s just an optical illusion. Or there’s an error in how Dan is producting his 3D graphs. Or we’re not understanding them correctly. Because it looks that way to me, too, but the underlying data doesn’t agree.