Monday, May 27, 2013

Why Do Some Plus (And Average) Fastballs Get Hit?

When working on my post on Kelvin Herrera and his 2013 home run problem, I didn't have a good explanation for why 100 MPH fastballs could be hit so easily. I have written enough posts about pitching velocity and why it is important, so we don't need to revisit the subject here. However, some elite fastballs do get hit, and there are even some elite velocity pitchers that still don't succeed. So it is worth knowing, or at least trying to figure out, why these fastballs do get hit at times. In an effort to find out, using (which is a great Pitch F/X website) I downloaded all pitches in the big leagues so far in 2013 (I think as of Saturday) that were thrown at 95 MPH or higher. On a side note, rather than using the traditional location Pitch F/X data, Darren Willman uses zones on his website.

Here are how I understand the zones (in a very simplistic form):

So I looked at the swinging strikes, run scoring plays, hits, and out plays on the 95 MPH + fastballs and looked at things like release point, location, and count to see if there was a common thread for which ones were successful, and which ones were not. Also, for comparison, I looked at every fastball thrown at exactly 91 MPH so far this year, what you might call league average, and looked to see if there was a common thread for successful average fastballs (you may have to click on it to get a full view of the chart)

 Not surprisingly, the 95 MPH + fastballs got more whiffs, and more of the 91 MPH fastballs were put in play. The same percentage of all pitches went for hits, which means that the 91 MPH fastballs have a lower BABIP. I can't really explain why this is the case, as the 91 MPH fastballs have a higher amount of run scoring plays, suggesting that they are being hit harder. This may just be randomness or small sample size. Oddly, the release points of the 91 MPH fastballs are higher than the ones of the 95 MPH + fastballs, and while the lefties are more out, the righties are closer to their body with their release points. 

When looking at the plus fastballs, the vertical release point is the same for all results.  For righties, there appear to be very little difference in horizontal release point, though the closest to the center of the rubber for lefties gets whiffs or outs.

Not surprisingly, even when looking at plus fastballs, the slightly faster fastballs on average are more likely to get whiffs. There is no real velocity difference between the ones that are turned into runs, outs, or hits. The zones suggest that the runs are higher than the rest of the pitches, though there isn't much of a difference between the whiffs and outs/no out pitches. Count, especially when it comes to balls, may be the best indicator, as the less amount of balls the better.

With the average fastballs, height was a bit of an indicator, with higher being preferable somewhat (though outs being better than whiffs and runs better than no out plays hurts the case). The zones broke down much differently than we saw the plus fastballs break down. The higher the number the better it seemed, meaning low or out of the zone got whiffs, while up in the zone gave up runs. It isn't surprising that location is more important for average fastballs than plus fastballs. Horizontal release points, whether left or right, really provided no help with the average fastballs. Count wasn't as helpful as an indicator as it was for plus fastballs as well. 

One thing this obviously doesn't take into account is hitters faced. We didn't look at platoons, and we didn't look at quality of hitter. By definition, better hitters will provide worse results for the pitchers on average. With that said, we didn't really see anything we didn't expect, though I thought release point would play a bigger role than it did. Getting ahead in the count early is very important for elite fastball pitchers, to just to keep hitters off balance and make sure they aren't sitting on the fastball. For average fastballs, location really provided the difference.


  1. it's got to be movement, which i dont believe you've discussed here. the few 100 mph pitchers seem to throw relatively straight balls. comment?

  2. So in response to your comment, I looked at the 95 MPH + pitches thrown so far this season (by the 31st I believe), and as far as vertical movement goes:

    Whiffs: 9.07 "inches"
    In Play, runs: 8.19
    In Play, out(s):8.16
    In Play, no outs:8.20

    So it doesn't really explain any batted ball differences, but it looks like there is something to whiffs and vertical movement for plus fastballs. Horizontal Movement is a little trickier to look at because lefties have "positive" movement (at least numerically the way it is measured) and righties have "negative" movement. You would want to separate that out. You would also want to separate the different kind of pitches as well, as sinkers and moving fastballs are generally going to get more horizontal movement, but also get less whiffs, which will play with the data obviously. You could look at just FF fastballs to tease that out, but I don't like relying on the MLBAM tags more than I have to, and I have been looking at all 95 MPH pitches.