Justin Verlander’s Slider Was Fixed Before Houston

During the Astros’ walk-off win on Saturday, Justin Verlander threw a 124-pitch complete game, which I didn’t think was allowed. Verlander piled up 13 strikeouts, and, of those, nine came on sliders. Verlander threw 39 sliders in all, 30 of which went for strikes, in large part because the Yankees swung at the slider 27 times. Verlander’s always been known for his fastball, and, in Game 2, the heat was there from start to finish, but the slider appeared overwhelming, with the Yankees having absolutely no answer.

This part’s almost obligatory. Let’s watch a couple strikeout sliders, if only just for the memories.

Sorry, Chase Headley.

Sorry, Todd Frazier.

There have been extended stretches in the past when Verlander has thrown a dominant curveball. There have been extended stretches in the past when Verlander has thrown a dominant changeup. These days, he’s primarily fastball/slider, and during Saturday’s game, John Smoltz mentioned that Verlander had improved his slider since arriving in Houston. Tom Verducci wrote about how Verlander had made use of Houston’s high-resolution cameras. So the story goes, Verlander went to the images and noticed he’d been throwing his slider differently. He then made an adjustment to generate more depth.

I don’t doubt that Verlander is currently throwing his best sliders of the season. He’s been exactly what the Astros wanted, and then some, an overpowering workhorse who pairs well with Dallas Keuchel to give the club a lethal 1-2 punch. So maybe this doesn’t really matter. But as far as I can tell, Verlander’s slider didn’t suddenly improve when he was traded to Houston. The improvement predated the deal, as Verlander made a midseason grip change.

The best place to conduct all this research is Brooks Baseball, so I’m going to borrow pretty heavily. Let’s get started, focusing just on this one Verlander pitch. Here’s how Verlander’s slider velocity has changed game to game, dating back to the start of last season. I’ve inserted a thin black line to mark when Verlander was traded to the Astros.

You can see that, earlier this season, Verlander was throwing his slider around or above 90 miles per hour. That’s the kind of velocity that tempts you to call it a cutter, but, in any case, Verlander then started to take something off. He subtracted around three ticks or so, and you can see that close to the middle of the year. Now, the left-most section might throw you off. Indeed, Verlander’s 2016 is confusing, because last year the slider was his most valuable pitch, and he threw it harder and harder and harder. For some reason, the hard slider that worked for Verlander in 2016 stopped working nearly so well in 2017. I don’t know why that is, but, there you go. The success of the hard slider was fleeting. So Verlander made a change.

Here’s a look at average vertical movement.

Again, focusing on 2017, you see a trend that predates the trade. It’s a trend in the direction of greater depth, mirroring the pattern seen earlier in velocity. Verlander made a change that allowed his slider to drop, on average, an extra two or three inches. What do you do with a slider that’s dropping more and more? You locate it lower. Here are Verlander’s average vertical locations, relative to the middle of the strike zone.

Verlander found his location in August. It makes sense — he made an adjustment, then it took him a little time to polish his command. Beginning in August, Verlander was able to keep his slider pretty consistently down. It’s the same thing he’s done in September and October.

Related to the change in slider behavior: a change in slider usage.

The slider frequency shot up in July. That’s around when Verlander changed his grip. And also related to the above: an increased ability for the slider to miss bats.

It’s all fairly unmistakable. Somewhere in or around July, Verlander made a change to his slider. He slowed it down, giving it more drop, and there was an immediate uptick in usage and whiffs. Shortly thereafter, Verlander refined his ability to keep the pitch down, throwing it more like a slider and less like a cutter. That’s what he’s continued to do as an Astro. And, now, I don’t have access to the same tools as Verlander. I don’t have my own high-speed cameras fixed on the pitcher during every delivery. But I’ve still managed to grab some screenshots. Here are a couple Verlander sliders from early in the season.

It’s not so easy to see how his fingers are aligned, relative to the seams, but compare those grips to these slider grips, from August, pre-trade.

A change is visible. By the later summer, Verlander gripped his slider where the seams narrow. It’s like a two-seam fastball, only with the index finger offset. This is a pretty common slider grip, but, for Verlander, it was an adjusted slider grip, from earlier in the year. And now here are two slider grips, at release, from Saturday’s Game 2.

It’s not the same perspective, which is kind of annoying, but I can only work with what I have, and what I have are the MLB.tv archives. As the ball comes out, Verlander seems to have basically the same grip he’d had in August. Gripped along the seams where narrow, index finger offset. Middle finger cuts through the ball, to give it its characteristic spin. Later in the summer, Verlander rediscovered a slider that allowed him to pitch like an ace. He hasn’t slowed down, running a 1.72 ERA over his past 15 appearances.

I know it doesn’t ultimately seem that important. Who cares when Verlander found his slider, just so long as it happened? But if anything, I think this helps to explain why the Astros acted when they did. I don’t think the Astros traded for Justin Verlander, hoping he would figure out how to throw a better slider. I think the Astros traded for Justin Verlander, having concluded he’d already found a better slider. Therefore, they had good reason to believe in his hot streak, because it was as if Verlander had once again found his own level. The Astros traded for Justin Verlander, believing him to once again be a capable ace. It might’ve seemed like a whale of a risk, but the Astros probably didn’t think it was that much of a gamble at all. Verlander had already done what he needed to do.