We’re almost done with April, which means we’re closer than we were before to being able to stop with the standard “it’s early” caveat we heartily employ during this time of year. For better or for worse, however, it’s still early. The good news (besides the obvious fact of it being April and baseball is being played) is that most starting pitchers have made enough starts to provide us with some sample of data to comb through for patterns and changes compared to last year. There’s still a lot of noise in that data, but there’s some signal, and we’re going to see what we can get out of a fun data set today.

It’s interesting news when a pitcher starts throwing a new pitch effectively, mostly because it happens pretty rarely. What’s also interesting news is when a pitcher starts throwing a pitch he already had in his arsenal more often, especially when he does so to an extreme level. With that in mind, let’s look at a table of starting pitchers, sorted by the percentage of sliders that they’ve thrown so far in 2015:



Holy smokes, Colin McHugh! Neil highlighted how McHugh is using his slider a couple weeks ago, and now we see Chris Archer slotted in the number two spot in terms of frequency of sliders used this season, at almost 40%. Anytime someone is at 40% usage of a pitch that isn’t a fastball, it’s noteworthy, and that’s part of why we’re here. Now let’s take a look at a chart, which tells us the percentage increase in slider usage in 2015 compared to last year (along with overall usage in 2015):

Justin Masterson has ditched the change up and gone full slider this year as he tries to reclaim his lost magic, and no one is really close to him in terms of slider rate increase. After him, we find a group between 9-14%, and that’s where we find McHugh and Archer, the latter of which has a very healthy jump of slider usage, at 10.7%. That jump has coincided with something else: velocity gain. For April, it’s a bit unusual to see this (courtesy of Brooks Baseball):

Archer is throwing both his fastball and slider harder than ever in 2015, with his slider in particular up a full MPH over last season. Again, it’s early, but velocity gains in the first few weeks of April are a little surprising, and not unpleasantly so. We now have have a trifecta of pitch usage for Archer’s slider so far this season: noticeable uptick in usage, reliance on the pitch as a main weapon (Archer has actually thrown more sliders than fastballs this season), and finally, velocity gain.

That combination works well when you have a fastball as good as Archer’s. The movement profile of Archer’s slider in 2015 is similar to 2014, though he has taken about an inch of vertical drop off of the pitch. His horizontal release point has shifted a few inches, so the slider looks a little tighter and closer to the movement of his fastball to my eyes. The main point we should focus on is this, however: he’s throwing it harder and way more often. Here’s what his slider looks like this year:

So how have Archer’s changes in velocity and usage of his slider affected its performance? Archer leads the majors this year in ground ball rate off of sliders at 63%, way up from his 50% mark last season. He’s also getting more whiffs per swing, at 41% compared to last season’s 37%. His ERA and walk rate aren’t going to stay this sub-humanly low for the entire year, but changes such as these to his peripheral numbers will go a long way toward increased success.

He’s now using his slider more in all counts and situations, but the biggest change is a 25% jump in two strike usage to left-handed hitters from 2014 to 2015. It’s now become his go-to out pitch against lefties — he’s currently throwing it 59% of the time to left-handers with two strikes. In those situations, batters are 0-14 so far this season with nine strikeouts. That sort of situational jump points to his increased confidence in the pitch, something no-doubt driven by his improved control and command: his 52.7% in-zone rate with his slider this year is much improved over 2014, when he posted a 39% rate.

It might not be too much of a surprise to hear that Kevin Cash had discussions with Archer about a pitcher Cash worked with during his time as a bullpen coach in Cleveland: Corey Kluber. It’s probably just a coincidence that Kluber and Archer now feature sliders that give them a great weapon against left-handed hitters. Regardless, Archer had this to say about his conversations with Cash in late February:

“We’ve had some good talks about things Kluber did to kind of really jump on the scene,” Archer said. “Kluber’s always had the stuff. He just hasn’t had success on that level. I’m trying to apply some of those things.”

Archer has been in the same boat: he’s always had the stuff, but walked a few too many batters to be up there in the elite tier of starting pitching. So far, his control has been much improved this year, and, with the addition of more ground balls and strikeouts from his adjusted slider usage, he could be set to take a step forward. He’s 26, coming into his prime, and now he’s throwing his harder slider 40% of the time. That sort of usage puts Chris Archer in select company, but I’m sure he doesn’t mind one way or the other. If the slider works, keep throwing it.