What’s going on with Gerrit Cole’s slider?

These Yankees may have some life in them yet. While a home series split with the Rays was not the ideal outcome of the last four days, the Yankees proved they can go toe-to-toe with the hottest team in baseball. In fact, the Yankees and Rays looked evenly matched in six of seven head-to-heads so far. The offense is heating up, scoring six or more runs in seven of their last eight, and hopefully the rotation will improve as guys get healthy.

That said, the Bombers are far from out of the woods, with several additional points of worry cropping up over the last week. Chief among those concern performances from guys expected to be stalwarts in the depleted rotation: Gerrit Cole and Nestor Cortes. My colleague John will cover the Cortes half of analysis tomorrow, so today the focus is the ace of the staff.

After looking borderline invincible across his first seven starts, Cole has been brought back to Earth by the Rays’ lineup in his last two outings. He’s served up two home runs in each contest after avoiding the long ball in his first seven, and his meltdown on May 7th squandered the six-run lead he had been given by an offense that was really in the weeds at that point.

I will not attempt to diagnose all the causes behind this pair of unfortunate results. Instead, I’d like to use today to investigate a trend that has persisted all season: the diminished usage and performance of Cole’s slider.

Ever since his trade to Houston — I use that as a cutoff point for evaluating Cole considering he was a fundamentally different pitcher with the Pirates than the version with the Astros and Yankees — Cole’s slider has consistently graded out as one of the best in the league. It perennially induces whiff rates in excess of 40 percent and sub-.200 expected batting averages.

This year is a different story entirely. The pitch’s whiff rate is cut practically in half from his average over the previous five seasons, from 40.6 percent down to 24.7 percent. His strikeout rate with the pitch is down roughly 15 points from the low 40s to 26.5 percent and its put-away rate has regressed about seven points.

Its overall usage rate is down about three points from the previous three seasons, and there are times when count leverage favors him throwing it, but he almost seems reluctant to use it in those situations.

Another way to visualize this is to look at his overall pitch mix in each count.

We see the same trend: Cole is increasingly reluctant to use the slider when he’s level or ahead in counts relative to last season.

These last two games against the Rays in particular highlighted scenarios that would typically call for a slider, but Cole almost seemed to lack that little bit of conviction in the pitch. Two at-bats in the first inning of his most recent start illustrate this point.

First we have the home run Randy Arozarena hit into the second deck.

It is immediately obvious from Arozarena’s swing 0-0 and check swing 0-1 that he was hunting a fastball, and his swing to leave the park confirms this. Cole still had count leverage in his favor at 1-1, even more so after seeing Arozarena’s reactions to the first two fastballs and remembering his sub-.200 wOBA against sliders this year. What better time to try for a chase with the slider? Yet Cole wanted none of it.

Later that inning, Cole faced Isaac Paredes and was lucky to keep his opponent in the ballpark. I’m only going to show video of the second-half of the AB for brevity’s sake.

After falling behind 3-1, Cole threw three straight fastballs to the exact same spot, and it became clear that Paredes was timing them up better with each one he saw. At this point, however, it’s almost too late to throw a slider. The time to throw it would have been directly after running the count full. Cole pounded him with three straight up-and-in and then shakes on the eighth pitch, almost telegraphing slider to the hitter. What’s more, it was a cement mixer that Paredes barely got underneath.

What is the reason for this seeming hesitance to use what was and should be one of the most feared pitches in baseball? In a word, command.

Cole is leaving an alarming amount of sliders up over the plate whereas he was the king of the gloveside-low corner last season. To the naked eye, he just does not seem to have acquired a feel for the pitch yet this season, and that’s exactly how he got punished in that fateful sixth inning at the Trop.

First was this slider to Paredes:

Trevino set up low and away and the pitch arrived middle-middle, allowing Paredes to line it for an RBI automatic double.

Then came the killer blow:

Once again, Trevino set up below the zone, yet Cole grooved a first-pitch hanger to Christian Bethancourt to cough up the rest of what was a six-run lead.

To his credit, Cole acknowledged the lack of command with the slider after that game. Unfortunately, he did not provide a definitive reason for the command deficit. However, when it comes to a pitcher of his talent, intellect, and dedication to his craft, I have every confidence he has been in the lab trying to iron out these issues, and it’s more likely than not we’ll see a return of his elite slider in the coming starts.