Cubs Hoping More Sinkers, Sliders Will Get Ryan Zeferjahn Right

The Cubs were confident enough in Ryan Zeferjahn‘s ability to stabilize their bullpen that they parted with Moises Ballesteros and righty pitching prospect Mason McGwire to pry him loose from Anaheim. Zeferjahn’s big strikeout numbers, elite fastball, and club control through 2030 made him a very attractive target, and the hope was that he’d see a bump in performance by moving to a real organization. Instead, he’s gone the opposite direction as his fastball suddenly became very hittable.

Seven of the 11 hits Zeferjahn has allowed with the Cubs have come on his four-seam, which is in stark contrast with the MLB-best .087 average and .109 slugging it had generated with the Angels. Part of the problem may have been an over-reliance on that pitch after coming over, something the Cubs’ pitching coaches have worked to correct. As Sahadev Sharma explained in The Athletic, Zeferjahn had leaned too heavily on his fastball and sweeper.

The goal is to have him allocate at least 30% of his pitch mix to his sinker and gyro slider, which had not been the case in his first seven outings with his new team. Zeferjahn has only thrown his slider in three of nine Cubs appearances, and he only threw four total sinkers prior to his last two games. He threw it six times in those outings, good for just over 35% of his mix.

There’s still a lot of work to do, as he gave up a run on two hits the last time out and hasn’t notched a strikeout in three games. In fact, Zeferjahn has failed to record a K in five of his nine Cubs outings. While the sample is very limited and thus subject to rapid correction, his 17.9% strikeout rate as a Cub is nearly half what he’d put up with the Angels (33.5%). At least his walk rate is down as well, though part of that comes from hanging too many pitches for hits.

That leads us to changes in his sequencing, the specifics of which are not detailed in Sharma’s piece. What was noted is that Zeferjahn needs to tighten up both his sweeper and slider a bit, as he’s not been getting around to the front of the ball as well as he and the Cubs would like. It’s all about shaking up his predictability, since it’s easier on the hitters when they’ve got about a 50-50 shot at guessing correctly.

Given their movement profiles and locations, one to the glove-side edge and the other to the arm side, it looks like Zeferjahn is looking to use his sinker after his sweeper. Five of the 10 sinkers he’s thrown with the Cubs have followed sweepers, three have followed fastballs, and the other two have led at-bats. That last bit is part of a trend that sees him throw the sinker very early in counts for the most part.

Only twice has Zeferjahn thrown the sinker after the second pitch to a batter, and one of those came on the third pitch. The only time he’s thrown it deep into an AB was against Tim Tawa of the Diamondbacks, when the sinker was used to get a groundout on the sixth pitch. Zeferjahn had also thrown Tawa a sinker after a sweeper to open the matchup, making it the only time he’s thrown that pitch twice to the same batter.

His slider usage is a bit harder to pin down because he’s only thrown five of them with the Cubs, but there might be a tiny clue in where he threw his last one. Two of those first four had followed fastballs, and the other two led off at-bats. When pitching against the Diamondbacks on August 24, Zeferjahn went sweeper, sinker, slider to retire former Cubs great Ildemaro Vargas.

The slider is a little firmer than the sweeper — 89 mph to 85 mph — and has a little more depth with about eight fewer inches of horizontal break, but it often ends up in a similar location because of where Zeferjahn starts it. Getting that slight separation in velo and movement with the sinker in between could be exactly what he needs to keep opponents guessing.

We’re still only talking about a handful of pitches here and there, so it all comes back to the fastball being more effective. If Zeferjahn can get things figured out, it’ll be a huge help to a bullpen that’s looked awfully shaky of late.