Sliders have platoon splits. The traditional slider does, at least. So opposite-handed hitters are always a struggle for the fastball/slider reliever.
That’s not really the case for Luke Gregerson. Though the throws his slider more often, percentage-wise, than anybody in baseball not named Sergio Romo, Gregerson has avoided platoon splits over his career for the most part. The right-hander has struck out 24.6% of lefties, and 25.2% of righties. He walks a few more lefties (9.6% vs 6.3%), but that’s not the profile of a guy who can only get righties out. How does he do it?
Luke Gregerson has three sliders.
“I change angles on the slider. Sometimes it breaks flat. Sometimes it breaks at an angle. Sometimes it breaks straight down,” Gregerson said about his main pitch. In fact, he said he has “a few different sliders” when pushed further. Depending on the handedness of the hitter, or where in the zone he’s looking to go, he’ll use any one of his sliders.
In a conversation I had with George Kontos about his slider, he said that his slider is more up and down since he had Tommy John surgery, and that he’s had an easier time getting lefties out than when he used to feature a more side-to-side slider. Gregerson agreed that he featured his downward-breaking slider more against lefties as well.
Can we see his three sliders in the PITCHf/x numbers? Thanks to Bradley Woodrum’s Tableau magic, here are his many sliders (from 2012 and 2013) graphed by x-movement, y-movement, and colored by velocity. I think you’ll see an up-and-down cluster at the bottom, a big cluster near the y-axis, and then a group of slow, sweeping sliders hanging out in blue on the right. No?
It’s still hard to separate the top two clusters well. If we do it just by location, and use k-means clustering to find ‘centroids,’ like friend Matt Dennewitz did, we can see three clusters, perhaps:
Using those three cluster centroids, we can identify three distinctly different sliders pitched in the same game. First, we’ve got the sweeping slider. This pitch, Gregerson’s ninth on April 12th this year, moved 5.43 inches horizontally and dropped 2.14 inches.
His fourteenth pitch that day moved two inches horizontally and dropped .86 inches. You might call this one his ‘flat’ one. Which is weird, looking at the GIF, but that vertical drop might be partly from the target — low and away.
And finally we have the up-and-down slider. This, the 19th pitch of his appearance, moved 6.01 inches horizontally and dropped 5.11 inches.
That’s one of the red dots furthest away from the centroid, however. Let’s see a ‘true,’ ten-inch drop up-and-down slider. This, from September 15th last year, dropped 10.97 inches and only moved 2.5 inches horizontally:
That’s definitively a different slider than the other ones. It’s almost a curve ball.
And really, that might be the lesson here. It must be very difficult to classify pitches. Gregerson takes a bit off, changes the angle, and has “a few” sliders that he throws. And yet we want to know ‘how many sliders’ does he throw, and we make big buckets so that we can say that he threw ‘exactly’ 69.9% sliders last season. But really, he has that one slurvey thing, that curve ball slider, and then the slider slider.
Not to get too Jeff Sullivan on you, but here’s one final GIF that should further make the point.
Once Gregerson dropped that pitch, Dick Enberg said “that’s the filthy slider.” PITCHf/x has that pitch moving 2.93 inches horizontally with 1.38 inches of drop. PITCHf/x also has that pitch as a fastball. Maybe Luke Gregerson has four (or more) sliders — and no fastballs?
With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.