Investigating Alex Sanabia’s Pitches

Last night, Alex Sanabia gave up a home run to Domonic Brown in the second inning, and as he was walking back to the mound, the video appears to capture him spitting on the baseball. Sanabia then proceeded to retire 14 more batters without allowing any more runs, and the Marlins beat the Phillies 5-1. Based on the video evidence, it seems as though Sanabia may have been throwing a spitball last night. Based on the fact that he had one of his best starts of the season, by results, it appears as though the spitball might have fairly effective.

Of course, this is all still highly speculative. We only have that one video clip of him spitting that one time, and because the clip is very short, we don’t actually know what happened before he threw the next pitch. Maybe he dried the ball off. Maybe the spit didn’t actually hit the ball, and it’s all a camera angle trick. If we’re going to assume that Sanabia was throwing a loaded baseball, we should investigate a little further.

Thankfully, due to the wonder of PITCHF/x, we can look at how Sanabia’s pitches moved last night relative to how they moved in his other starts the rest of the year. No pitcher is loading up and throwing a spitball on every pitch, and the entire point of putting additional moisture on the ball is to give it irregular movement, so if Sanabia threw a spitball last night, there should theoretically be some evidence of it in the PITCHF/x data.

Here are Sanabia’s game charts from last night.

And here are Sanabia’s same charts for all of his 2013 performances.

Now, let’s overlay the images on top of each other, so you can use your mouseover to see the difference between his seasonal movement charts and the charts from last night.

There’s certainly two weird looking areas on the vertical movement chart, but those are all from the same game – his April 5th start against the Mets. Given that all of those outlier pitches came from the same start, I think we can safely assume that’s just a data error, either with the PITCHF/x calibration that night or the numbers that got stored in the database.

Take away those two blobs, and everything else looks pretty normal. His pitches from last night are in the same general range of movement as they have been in all of his other starts this year.

What if we focus on the pitch immediately after the apparent spitting was recorded? Delmon Young came up to bat against Sanabia after Domonic Brown’s home run, and Sanabia threw him a first pitch fastball, at 88 mph, taken for a ball. Here is the horizontal and vertical movement of that pitch, courtesy of TexasLeaguers.

And here’s all the sinkers that Sanabia threw last night.

And, again, here’s the images overlaid on top of each other.

In terms of vertical movement, it was a totally normal fastball from Sanabia, relative to all the other fastballs he threw last night. In terms of horizontal movement, it is on the edge of all the fastballs he threw, but not dramatically different than the rest.

Of course, that could just mean that Sanabia spit on a few other baseballs, so the lack of an outlier could be due to multiple spitballs making each one look like less of an outlier. Or, it could just be that Sanabia’s spitball didn’t really do much for him after all. While it’s easy to note that he only gave up one run in 6.1 innings, we should also note that he only struck out three batters and allowed a .300 BABIP, so it wasn’t like he was unusually dominating last night.

If we were looking for a smoking gun in the PITCHF/x data, I don’t think there’s one to be found here. MLB might already have the smoking gun considering the video from last night, and in terms of a punishment, it shouldn’t really matter whether Sanabia threw an effective spitball or not, but I do think it’s at least informative to know that his pitches didn’t seem to do anything all that weird last night. If we didn’t have that one second video clip, I don’t think anyone would have thought Sanabia was loading up the baseball otherwise.

But, of course, we do have that video clip, and it sure looks like Sanabia spit on the baseball in that clip. That evidence is probably more compelling than the PITCHF/x data. But, at least from my look at the pitch movement plots, it’s not completely obvious that Sanabia was throwing anything all that different from what he’s thrown all year.