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October 5, 2009

Checking the Numbers

Location and Perception

by Eric Seidman

The velocity recorded by the radar gun and what the batter perceives do not always match. As discussed previously, several factors can cause a pitch to appear faster or slower to hitters. One such factor is the flight time from the point of release to when the ball crosses home plate relative to the flight time the PITCHf/x system projects at 55 feet away. Pitches released any closer than this predetermined distance result in a higher perceived velocity with the inverse true of pitches let go from distances greater than the default. During our initial look it was observed that a few pitchers generated perceived velocities dissimilar to their recorded velocity, a proof of concept that was much more important than the velocity discrepancies themselves. Johnny Cueto, for example, averaged 92.9 mph with a perceived 90.8 mph, while Ian Snell found himself perceived to throw just 87.6 mph in spite of the reported 91.7 mph. But where Snell threw these pitches must also enter the equation, since the location of a pitch works in conjunction to the flight time to add or subtract perceived miles per hour.

Intuitively, the idea of lateral location affecting perception is not entirely new, as scouts and commentators have often remarked that an inside pitch will seem faster than one on the outside, that higher pitches will appear to have more giddyup than those on the lower half, and that the spread of these two pitches can create a relative velocity that helps pitchers maximize effectiveness. Determining the appropriate quantification techniques is what has eluded analysts, leaving unanswered the question of how to measure this qualitative information. It is valuable to learn that pitchers can add or subtract velocity based on location, and that the velocity differential between a fastball and a changeup might be much greater or lesser than it appears to be if the pitches are sequenced in a fashion that subtracts from the fastball and adds to the changeup.

The idea of location-based perception comes from a man named Perry Husband, who has a series of books on what he calls "effective velocity," a concept similar to what we are discussing here but different enough that a marriage of our methods will help produce truly optimal results. Husband’s studies on hitting led him to quantify the various perceived velocities based on different spots in the zone, and a summary of his work in this area is in order before moving onto the nitty-gritty. In its simplest form, his calculations are based on the idea that for every location only one point exists at which a batter can achieve perfect contact, meaning the lead arm is fully extended and the sweet spot on the barrel of the bat meets the ball.

As the locations change throughout the strike zone, hitters either need to speed up or slow down their mechanics in order to achieve this type of contact. As pitches get closer to the hands, the perceived velocity increases because the hitters need to adjust the swinging mechanism in order to connect the ball with the sweet spot. On the flip side, pitches located further from the hands afford more reaction time, decreasing the perception of velocity to the hitter. Combine these increases and decreases with what was experienced when measuring the flight time perceived velocity and the net is a more advanced representation of the velocity hitters are actually experiencing. Via Nick Piecoro, a writer for The Arizona Republic, catcher Miguel Montero relayed to me his thoughts on the matter:

It’s harder to react to it, to be quick enough to turn on it. If it was a fastball outside, you can just throw your hands at it. But when it’s a fastball inside, it’s too tough to just throw your hands at it. That’s why a fastball inside is one of the hardest pitches to hit if you can locate it.

These reactionary changes—or as Montero put it, whether or not a hitter has time to throw his hands at a pitch as a means of reacting—suggest that the hitter experiences a shift in his abilities to see the pitch, to decide whether or not to swing, and to execute a swing capable of making the optimal form of contact. A pitch thrown directly down the middle will have a location-based perceived velocity equivalent to that which was measured from the flight time, so if Chris Young threw a pitch down the middle and belt-high with a perceived velocity of 88.7 mph, the location would not affect the perception in any form. Move that pitch six inches in on the hitter from the original spot, and according to Husband’s studies the hitter needs to hit the pitch 18 inches further out in front by comparison. The diagram below can offer an even better explanation of how the changes in locations—or lanes in the strike zone—affect the timing of a hitter’s swing relative to where perfect contact can be made: