Blake’s Breakers: How a new Yankees slider has swept away the competition

By virtue of the announcement coming during Carlos Rodón’s introductory press conference, news of the Yankees re-upping pitching coach Matt Blake a few weeks ago flew under the radar. Blake, who signed a second three-year contract, has been credited with the Yankees’ adoption of the “whirly,” or sweeping slider, which has instigated an improvement in the club’s ability to limit hard contact.

The pitch, which has more horizontal movement than a typical slide piece likely due to a special kind of additional drift created by seam-shifted wake, is known to induce popups at a high rate and thus can lower a team’s batting average on balls in play (BABIP). Clubs began employing the sweeper more often in 2020. Since, overall slider usage has risen and slider BABIP has fallen. But the Yankees represent something of an exception to this trend despite their use of the whirly, and it’s because Matt Blake has been running his own experiment since he first signed on:

During the last three years of Larry Rothschild’s run as pitching coach, 2017-2019, the Yankees threw the slider less and less and the BABIP jumped around. In his first season, Blake began by having the team throw the slider less and less in 2020 and 2021, but then, after he perfected the whirly with a big decrease in BABIP from 2020 to 2021, he started utilizing it more often again this past year. Blake has worked BABIP magic throughout his tenure, with a top-nine mark for the staff in each of his first three seasons. Polished whirly in hand, he took his wizardry to new heights in 2022, with the Yankees’ BABIP tying for second-lowest in the majors. As a result, the club’s ERA ranking handily outpaced that of their FIP (which controls for usually-finicky BABIPs) for the first time during Blake’s tenure. Additionally, their ERA rank has improved each year of his stint as pitching coach:

Given the finickiness of BABIPs, how much of this is sustainable? After all, the Yankees’ slider BABIP drop has outpaced the league’s in each of the past two years. But there’s something different about the Bombers' employment of the pitch that makes me think its improvements will stick. While the league has moved towards sliders and away from sinkers, the Yankees have moved towards both:

Sinkers and sliders typically go hand-in-hand due to the spin-mirroring effect. Essentially, it’s possible to get them to spin on near-opposite axes, around 180 degrees apart, which leads to movement in opposite directions but is extremely hard to differentiate for a batter. Why have the Yankees been pairing sinkers with the popular slider, but other teams haven’t? Well, not only do the Yankees get closer to the optimal 180-degree difference on average, but they also get a larger movement differential between the two pitches (min. 100 total sinkers plus sliders for each pitcher included):

Something else that these results made me wonder was why, if the Yankees’ sinker-slider spin axis differential was eight degrees greater than the league’s on average, their observed movement differential was less than one degree greater. One possibility is that it might be tougher to generate increasingly greater movement once you approach the extremes; perhaps the effects of additional forces such as seam-shifted wake are also limited at that point. Another is that emphasis on spin axis differential might come at the cost of some extra movement. Whatever the reason, on the whole, the Yankees still have a slightly larger movement differential than the league and a significantly larger spin axis differential; their sinkers and sliders are harder to discriminate among throughout their trajectory but especially upon release.

In short, the Yankees’ hiring of Blake has paid off. Seen as risky at first due to Blake’s relative inexperience, his (limited) reputation as a rising star among analytically-inclined coaches has proven accurate. But what drew the Yankees to him specifically was how personable he seemed. Seeing as a huge part of today’s game on the pitching side includes customized plans, the connection between coach and player is certainly still key. Big picture, that also means the whirly won’t be for everyone. It’ll be Blake’s job to decide who leans on the pitch (for example, will his press conference partner Rodón?), and if the past three years are any indication, he’ll make the right choices.