Dylan Cease’s new slider is smashing records

We know Dylan Cease is having a great season.

It's also possibly a historic season.

It's not historic in the way you'd probably expect. His 2.01 ERA and 161 strikeouts are fantastic, to be sure, and his 3.8 rWAR puts him in a tie with Justin Verlander for the AL lead. Only Shane McClanahan has him beat in Baseball Prospectus's WAR equivalent (WARP). It's great company, but nothing record-shattering. We'll get to that in a moment.

There are a number of reasons the 26-year-old is finally making good on the stuff that scouts have long pinpointed as some of the nastiest in the league. One element in particular stands out that's already been observed by a number of others:

All of a sudden, Cease's slider has become perhaps the majors' most effective pitch.

Nobody seems to know it better than Cease, who threw a season-high 59 sliders on Sunday, the second-highest total for any pitcher this season.

It's hard to understate the slider's dominance. Nearly half (47%) of the swings taken at it are misses, and just five of 111 balls in play on it have gone for extra bases (.166 slugging percentage). It's almost unprecedented in its combination of heavy usage (fifth-highest among starters, at 42%) and elite effectiveness. Since pitches began being tracked in 2008, only two pitchers have thrown as many sliders as Cease with a lower wOBA than his .154. Those two? CC Sabathia in the year of his quasi-legendary post-deadline run with Milwaukee in 2008, and the 6.8 rWAR campaign that netted Clayton Kershaw the first of his three Cy Youngs.

He's followed up on that list by the 2018 season that saw Chris Sale break Pedro Martínez's 20-year-old record for strikeout rate (min. 150 IP), and the 251-inning, 24-win warpath that resulted in an MVP/Cy Young double-dip for Justin Verlander in 2011. Quite the company, to say the least.

As far as records go? It's about more than WAR, wOBA, or other difficult-to-parse rate stats. The slider's expected stats are excellent, as are its whiff and strikeout numbers. But let's talk about overall results, and why Cease is having a unique season even outside the context of his own career path.

Kamil Krzaczynski-USA TODAY Sports

You may have seen a stat called "Run Value" being thrown around lately as buzz starts to grow about Cease’s All-Star snub. Run Value (RV) is a great way of assessing how good a pitch has been in terms of pure results.

How does it work? It's actually pretty simple: With the availability of tens of thousands of box scores dating back many decades, it's possible to calculate the probability of a run (or runs) scoring for any combination of count, outs, and runners on base.

For example, with a 1-1 count, one out, and a runner on second base, history tells us we'd expect the offense to score 0.67 runs — a bit more than a 50/50 shot of getting on the board.

We can use this information to tell us how often an individual pitch is getting good results.

Take that previous scenario. If that 1-1 count moves to 1-2, the expected runs drop to 0.58. Let's say that 1-1 pitch was a slider. We can now say that the slider reduced the number of expected runs by 0.09 runs. Conversely, if the pitch is a ball and the count goes to 2-1, it moves up to 0.72 expected runs. If they throw the slider again and it becomes a 3-1 count, it shoots up to 0.79, and we can say that the slider has added 0.12 expected runs.

Over the course of hundreds of pitches, those small sums add up to something bigger. In this case, a negative number is a good thing — it means a pitch is preventing runs. Now, reader, I present the Baseball Savant leaderboard for expected runs prevented on individual pitches.

Baseball Savant

Oh me, oh my. A 10-run margin at the top is exactly as ridiculous as it seems. And according to FanGraphs, which uses different information that Statcast for calculating run value, Cease is nearly tripling up his nearest slider competition.

FanGraphs

Interestingly, note as an aside that Cease's fastball hasn't actually been all that effective this season! That's how filthy the slider has been.

Is there any kind of historical precedent here? Not much. With two months left to rack up stats — it is cumulative, like WAR — and presuming no late-season fall-off in effectiveness, Cease is just a good outing or two away from shattering the record for slider run prevention in a season.

Baseball Savant

It’s a shame that Armando Galarraga could have had another claim to fame this entire time. Now, the poor guy can’t even get a Savant head shot.

Anyhow, with at least eight starts remaining, Cease ought to make a serious run at Kershaw's modern record of -36.7 runs racked up against his fastball in his 2013 Cy Young redux. In the FanGraphs calculation, Cease probably won't be able to mount a challenge to the 2002 season in which the Big Unit won his fifth and final Cy Young Award at age 38, but he still has a legitimate chance to post one of the two or three most effective slider seasons since Baseball Info Solutions began tracking pitch types in 2002.

FanGraphs

There are limits to these stats. They're not predictive, which means it doesn't tell us anything about how good Cease's slider might be from this day on. But it does tell us that it's been historically dominant up to this point. It's always been a good pitch, but to carry his arsenal like this? I have no concrete answers, but a quick dive under the hood tells us a little about what's allowed him to reach the next level.

Patrick Breen/The Republic

Two months ago, James Fegan of The Athletic gave us an excellent look at some of Cease’s slider adjustments, profiling the changes the righthander made “to get more depth” on the pitch. Perhaps of note, this was just prior to the start against Los Angeles that kicked off his historic run. The upshot is that at the end of May, Cease lopped off a fair amount of vertical and horizontal break from the breaking ball, to quite a bit of positive effect. Looking now, it seems to have held up through the subsequent two months.

Why is this happening? Underneath the movement numbers, we can also find some substantial changes to the slider's physical properties.

First, within Fegan’s piece, pitching expert Eno Sarris pointed out that Cease was suddenly throwing his slider measurably harder, which current research indicates is typically a good thing. It tracks well logically — giving a hitter less time to react on a pitch that moves a lot can only be to the pitcher's benefit. That too seems to have held up through the second third of the 2022 season.

Another important factor is active spin — that is, how much of the spin he’s putting on the ball is actually causing movement.

Even without sticky stuff, Cease has some of the highest spin rates in the league, which is a large part of why his fastball and curveball are as electric as they are. Those pitches have high active spin rates on top of their regular high spin, which means most of that spin is turning into movement.

His slider, however, has gone in the opposite direction, dropping from 50% active spin in 2020 to 39% in 2021 and settling in at 28% so far in 2022. This is the kind of change you only get by releasing the ball out of the hand differently, another suggestion made to Fegan by an unnamed scout. Because it spins at a top-of-the-scale 3000+ rpm when Cease rips off a good one, the effect has been to neutralize just enough of that spin to straighten the pitch out a touch — which may make it easier for him to command, another factor that Cease has repeatedly cited this summer — while retaining more than enough movement to make it unreasonably hard to square up.

Making a sharp slider more straight might seem counterintuitive, but the effects seem to have been positive. First, we should see what the difference actually looks like on video. Here we have a slider thrown to Twins catcher Ben Rortvedt in July 2021.

Following that up, we have a slider thrown in 2022 to another left-handed hitter, Jorge Polanco, in the same stadium with an identical camera angle.

The difference is subtle, but clearly visible to me. The 2022 iteration has a less slurvy bend to it, moving like a tighter, more traditional up-and-down slider. For good measure, here's another one from this year, in which Byron Buxton seemed to anticipate the pitch being just a couple inches more outside than it actually was.

What’s the actual effect of these changes? How is this fueling his monster season?

If there’s one thing we can say for sure, it’s that Cease is not challenging history by filling up the strike zone. He still leads the league in walks, throws the ball in the zone 5% less than league average, and he’s throwing the slider out of the zone slightly more now than he was last season. The difference? Hitters are hacking at it more than ever before, going from a 39% swing rate in 2020 to 44% in 2021 before rising to 51% in 2022.

For a pitch as nasty as Cease’s slider, that’s a very good thing. Unless said slider is right down the middle and the hitter is sitting on it — not an easy proposition with a 98 mph fastball and 60-inch curveball — more swings means more bad swings. Hitters are chasing his slider out of the zone 40% of the time, up from 35% last season, and when they chase, they’re whiffing a full two-thirds of the time. When they do put it in play, they’re 2-for-26, a marked improvement from last season’s 8-for-20.

That aspect may be a testament to Cease’s increased confidence in commanding the slider consistently. Looking at side-by-side heat maps of his sliders out of the zone shows a small adjustment from the side of the strike zone to slightly more below it.

It’s not a huge shift in a purely spatial sense, but it’s a game of inches, and those couple of inches can be the difference between a rally-starting hit ...

... and a no-chance whiff.

Cease’s command still isn’t particularly good — he does lead the league in walks, after all — but it’s evolved to the point where it’s good enough to let his stuff do its thing and get positive results. Take his slider with two strikes. Last year, if a hitter recognized a slider with two strikes, it was a pretty solid bet that the pitch was going to be a ball.

In 2022, a hitter that picks up on a slider with two strikes has a much tougher swing decision on his hands.

It’s not just on two strikes, either. Forget chase rates — hitters have also become way more inclined to offer at Cease’s slider when it’s inside the strike zone, swinging a full 10% more there than they did in 2021. The phenomenon is particularly evident in the bottom third of the strike zone, where hitters are swinging at a Cease slider 79.5% of the time after doing so at a 61% clip last year.

Unfortunately for them, results on sliders in the zone are much the same as when they swing at it out of the zone: They don’t make much contact (he ranks third among qualified starters in zone swing-and-miss rate on sliders), and when they do make contact, it has the worst expected wOBA of any slider in the league. Damned if you do, damned if you don’t. It doesn’t matter where it’s thrown. Hitters want to swing at it, but they simply haven’t gotten any good wood on it.

Cease’s 30 runs saved aren’t some kind of fluke: By definition, adding a bunch of easy outs is going to add a bunch of run value at the same time. There’s simply been no route to success against this pitch in 2022.

There are many other things at work pulling it all together for the long-enigmatic 26-year-old. Perhaps the slider’s new shape makes it tunnel better with his fastball, making hitters misidentify the former to the effect of a bad swing. Perhaps the extra velocity and more up-and-down movement is making hitters see the pitch as a strike (whether it’s in the zone or not) much more often than they have in the past. Only those who have faced him can tell.

All the same, we have more than enough information to satisfy most of my curiosity. Not only do we know the driving force behind Cease’s breakout, we know exactly how that driving force came about, and what it’s doing now that it wasn’t before. Fegan concluded his early June article with the observation that “Frankly, it doesn’t seem like the full returns have even arrived yet.” Two months later, the returns might be even better than the most optimistic of us could have imagined.