I’ve tied up some of the loose ends from my first post on Jonathan Papelbon, and I wanted to share those findings here.

First, I mentioned that polar plots were preferable to standard x-y plots when graphing spin direction, measured in degrees. I’ve decided that is untrue. The polar plot does a better job of conferring the idea that we’re looking at an angle, but the x-y plot does a better job of spreading the data out for examination, and that seems to be more important for pitch classification.

Second, at the time of the first article, I had not classified the major pitch types. Now I have, and what I found was consistent with the scouting reports. Papelbon’s main pitches are his four-seam and two-seam fastballs. Against lefties, he uses his split-fingered fastball as his offspeed pitch, and against righties, he uses the slider as his offspeed pitch, mixing in a few curves and a few splitters (and slutters?).

I didn’t find any strong evidence of a slider/cutter hybrid, the semi-famous “slutter”. I found two pitches sitting on the edge of the slider group that had a much higher spin rate. (Actually, the slider often has a significant component of spin with its axis along the direction of travel, which we cannot measure. These pitches may have the same spin rate as the slider but as sidespin rather than spin along the direction of travel.) These might be the slutter, but with only two instances, I’m hesitant to say.

Without further ado, here is the graph reprised from the previous post, with pitch types marked. Also, pitches to lefties are shown in red, and pitches to righties are shown in green.

Papelbon Speed vs. Spin Direction with Type

The four-seam fastball is thrown the hardest, running 94-99 mph. It has the highest spin rate, about 2800 rpm. This is mostly backspin but also some sidespin that suggests it’s coming from a 3/4 delivery. It rises the most compared to a theoretical pitch without spin, about 12 inches on average, and rides in on a right-handed hitter by about 7 inches.

The two-seam fastball is thrown slightly slower, roughly 91-95 mph, with a slightly slower spin rate, about 2200 rpm. This pitch has about equal amounts of backspin and sidespin. It “rises” a little less than four-seamer, only about 9 inches, and rides in on a righty by about 8 inches.

The split-fingered fastball is thrown about 84-91 mph, and has a much slower spin rate, between 1000-2000 rpm. The splitter has a significant amount of sidespin. Compared to the other fastballs, it has a large drop. Compared to a pitch without spin, it rises about 2 inches and breaks away from a lefty by about 8 inches.

The slider is thrown about 81-88 mph, and has a very slow spin rate in the x-z plane that we measure. This is mostly backspin, but as mentioned before, much of the actual spin is probably around the direction of travel, as is typical for a slider. The slider “rises” by about 5 inches compared to a pitch without spin and breaks away from a righty by an inch or two.

The curveball is thrown 78-81 mph, and has a very slow spin rate of about 600 rpm. This is mostly topspin, with a component of sidespin. The curveball drops a couple inches and breaks away from right-hander by about 3 inches.

The two slutters, if in fact that is what they are, were thrown at 85 and 92 mph, with a spin rate of 2200 rpm. They had mostly backspin, rose 11-12 inches compared to a non-spinning pitch, and broke in on a righty by 0-2 inches.

Finally, moving on to a third topic, I found that the “release point” (initial position) data was not very helpful in classifying pitch types. The groupings we saw in the previous article were due to park variations. The park-to-park dependence washes out anything else. Josh Kalk’s work on correcting for park variance is going to be very important. To drive home that point, here is the initial horizontal position, x0, for all of Papelbon’s pitches since the All-Star Break, when the y0 distance was set to 50 feet. Notice the strong dependence on park above all else.

Papelbon Release Point by Park

I’m not completely sure if the data is consistent even within one park. Note how the initial position has increased between the first stint in Boston and the second stint in Boston. It’s possible Papelbon changed his release point during this time, but given the other inconsistencies in the data set, my confidence that it’s not a system change is not very high.