Dylan Cease Is Having a Strange Seasonon September 14, 2020 at 5:30 pm

Dylan Cease Is Having a Strange Season

Dylan Cease has a simple calling card: a four-seam fastball that he throws in the upper 90s. Every prospect evaluation of Cease centered on the heater, a bludgeon he would use, the theory went, to leave hitters with no good choices. He backed it up with a curveball and a developing changeup, but those were the backup dancers; the fastball was the star everyone came to see. There were questions about whether he’d be able to make the whole package work, but if it did, the heater would be the reason why.

Nine starts into his sophomore season, however, things haven’t gone according to plan. Cease’s 15.4% strikeout rate is the fourth-lowest among qualified starters, ahead of only Mike Fiers, Antonio Senzatela, and teammate Dallas Keuchel. The White Sox probably hoped Keuchel would help mentor their pitching staff, but uh… not like this. On the other hand, Cease is running a 3.33 ERA, better than team ace Lucas Giolito. Huh?

In an even stranger development, Cease’s fastball appears to be the culprit behind his poor strikeout rate. Though it hasn’t lost any velocity — his 393 four-seamers this year have averaged 97.4 mph — the pitch simply hasn’t missed any bats. Here are the 12 pitchers with the lowest whiff-per-swing rates on their four-seamers, as well as their average velocity:

That’s not a list of bad pitchers. It is, however, disconcerting to see a fastball-first power pitcher sharing space on a list of contact-heavy fastballs with literally Zack Greinke. Cease has an absolute cannon, but he isn’t missing any bats with it.

The first place my mind went was spin. The advent of Statcast has had one overarching effect on pitcher analysis: it introduced pitcher spin into the “look at this thing first” category along with velocity and location. Could Cease’s issue be a lack of spin?

Nope! He’s actually seventh among all starters in four-seam spin rate. Some of that is due to the relationship between velocity and spin — faster fastballs spin at a higher rate in general — but even if we look at Bauer Units, a Driveline Baseball creation that is just a branded way of saying spin divided by velocity, he’s in the top quarter of pitchers who have thrown 200 or more four-seamers this year, in a statistical dead heat with Gerrit Cole.

What gives? It’s time to take a dive into active versus inactive spin, and I sincerely apologize for all the visualizing I’m about to make you do. If you already know this part, feel free to skip ahead a little, but it’s a point worth talking about in an era where spin rates are at our collective fingertips on Baseball Savant.

Imagine a football flying through the air, thrown in a perfect spiral. The football has tons of spin — you can’t make out the laces as anything more than a generalized blur. That spin, however, doesn’t create movement. The ball flies true. It’s called gyroscopic spin, or “inactive” spin for our purposes. That means that it doesn’t contribute to the ball’s movement (aside from a small secondary effect due to the ball’s movement vector changing during flight, which I’m going to ignore today).

Active spin, or transverse spin, is the opposite. Think of a tire on a road, or a tennis ball hit with pure topspin. This spin directly alters the ball’s trajectory — pure backspin pushes the ball higher than a spin-less path, pure topspin pushes it directly lower, and so on. This is the spin that rising fastballs use so effectively — batters track the path home, but find only air when they swing because spin has lifted the ball out of the way.

For an example of this, consider 2020 spin king Trevor Bauer. As you can see from the leaderboard above, he has the highest four-seam spin rate among pitchers with 200 tracked fastballs (teammate Lucas Sims takes the crown if we lower the threshold). Using this handy research from Alan Nathan, I measured Bauer’s transverse spin on each fastball he’s thrown in 2020. He generates 2175 rpm of active (transverse) spin on average, roughly 80% of his total spin (there appear to be calculation differences between Nathan’s method and the one used on Baseball Savant’s pages, so for clarity’s sake I’ll be using Nathan’s approximation for every reading in this article).

You can probably guess, based on all the setup work I’ve done here, that Cease is an outlier when it comes to active spin. Bad news for White Sox fans, though: he’s an outlier in the way you don’t want. Cease’s fastball might spin a lot, but it’s mostly gyroscopic spin. He generates 1310 rpm of active spin, 53% of his measured spin. Something in his mechanics is putting a lot of the spin he applies to the ball into gyro spin, something I’ve come to think of as the Corbin Burnes effect.

Why doesn’t Cease’s fastball miss bats? It doesn’t move enough. He’s cutting the ball too much — cutters have a far higher percentage of gyroscopic spin than four-seamers. He doesn’t get the benefit of a cutter, though, because cutters move much less than batters’ brains expect. Cease’s fastball merely moves to where they think it should. The pitch exhibited the same characteristics last year, too, so it’s not some new mechanical issue; rather, that’s simply how Cease has thrown the pitch in all the major league data we have available.

If Cease’s fastball isn’t missing bats, then, why has he been so dang good? Why bother talking about his strikeouts and his fastball when he’s preventing runs so well? Unsurprisingly, things aren’t quite as rosy as that ERA under the hood. Cease has a 5.95 FIP, and it’s not due to bad home run luck on fly balls — his xFIP, which applies a league-average home run rate, checks in at 5.81. His SIERA, a fancy-schmancy version of xFIP that shares the ERA scale, checks in at 5.72. If you’re a fan of Statcast metrics, his xERA is in the 17th percentile, his xwOBA allowed in the 18th percentile. That’s really bad! Worse, even, than a 3.33 ERA is good.

What gives? I hate to spoil such an interesting mystery with a bland answer, but it comes down to luck. In Cease’s case, specifically, three things are working his way. First, he’s allowing only a .233 BABIP. Pitchers certainly exert some control over the batting average they allow on balls in play, but not much, and certainly not enough to account for Cease’s .233 mark. He allowed a .323 BABIP last year, Statcast’s xBA thinks he should have allowed a .310 BABIP so far this year, and Depth Charts thinks he’ll allow a .312 BABIP the rest of the year. There’s simply no indication that this streak will continue.

Second, a disproportionate number of his runs allowed have been unearned. Pitching is a game of run prevention, not earned run prevention. Swap a single in one inning for an error in another, and nothing changes about the number of batters who reach base, merely whether the runners would count as earned or unearned runs if they scored. In baseball as a whole, 92% of runs allowed are earned. Cease, however, has four unearned runs out of his 21 allowed. That’s something like 2.3 runs that don’t count against his ERA even though they count against the White Sox on the scoreboard.

Finally, there’s a factor that ties heavily into run prevention that we haven’t talked about yet: leaving runners on base. Cease ranks in the top 10 for LOB%, the percentage of batters that reach base but don’t score — league average is around 72%. Everyone in front of him is a strikeout monster:

LOB% isn’t random! Pitchers who allow fewer baserunners run higher LOB rates for obvious reasons. When Shane Bieber is confronted with the bases loaded and two outs, he has a big edge over your average pitcher: he’s phenomenally likely to strike out the next batter. He’s also unlikely to walk him. His OBP allowed, in other words, is lower than average, which means his odds of getting an out on a given batter are higher than average.

Cease doesn’t have that skill. He has one of the lowest strikeout rates in baseball, remember? He’s also walking more than 10% of opposing batters — no help there. As we saw above, he’s benefiting from some incredible BABIP luck, which has lowered his OBP allowed — but if that breaks back to normal, this rate could go south in a hurry.

Give Cease a league-average LOB%, and he would have allowed six more runs so far this year. But he might not even deserve a league-average rate: the aforementioned low strikeout rate is a headwind here. Being a fly ball pitcher helps somewhat — fly balls run a lower OBP than grounders — but only somewhat, because they both can’t induce double plays and lead to more home runs. In other words, don’t get on this to continue.

So what’s up with Dylan Cease, prospect extraordinaire with a dynamite fastball? He’s become Dylan Cease, strikeout-poor starter who has induced a boatload of poor contact with runners on base. The White Sox would love to see that pattern continue. If they’re honest with themselves, however, I don’t think they believe it can. Cease will need some work, somewhere — perhaps in his fastball grip, perhaps in an improved secondary pitch — to avoid the fate of so many LOB% and BABIP overachievers before him.

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