Game 137, White Sox at Mariners

Michael Kopech vs. Luis Castillo, 1:10pm

The M’s continue to benefit from nearly untouchable starting pitching. Their starters have a 3.29 ERA/3.27 FIP since the start of August, a performance which, if anything, undersells how good they’ve been. Similar to the surging Rays, the M’s starters have been excellent at limiting free passes. This has helped produce a dominant set of numbers. M’s pitchers have allowed a wOBA of just .281 since August 1, 5th best in the game, and just behind the juggernauts in Houston and Los Angeles. Their starters, led by Kirby and last night’s starter, Logan Gilbert, have essentially stopped walking people. This means that the hard-hit contact they give up, and they give up kind of a lot, occurs in situations least likely for that contact to hurt them.

But the real stars of the past six weeks have been the bullpen. We could’ve said that at several points over the past few months, but look at this. The ‘pen can take a very different approach. The bullpen is fine giving up walks, or at least, they give up more of them than the starters, but they absolutely smother quality of contact. The M’s pen has the lowest average exit velocity in the majors by over 2 MPH since August. The gap between the M’s and #2 is the same as the gap between #2 and #19.

Michael Kopech came up as a flamethrowing super-prospect, the centerpiece (along with Yoan Moncada) of the Sox trade that sent Chris Sale from White to Red. Famous for his top-of-the-scale velocity, Kopech has battled injuries off and on, but become a solid pitcher. That’s perhaps less than the White Sox hoped for, but more than looked possible when Kopech was rehabbing TJ surgery or another arm injury. He looked to have turned a corner last year, producing dominant K:BB numbers in a (wait for it) bullpen/spot-starter role. Limiting walks, something that had troubled him in the past, made him a potential Cy Young candidate in 2022, albeit potentially as a closer. How would starting full time impact him?

Well…it’s not been great. Kopech doesn’t have the top-end velocity anymore, and certainly not as a starter. He’s above average, for sure, but it isn’t overpowering. And what’s worse is that he doesn’t know where it’s going. All of his control gains from last season have been frittered away, as he’s now sporting a K-BB% of 9.4%, down from 27.7% last year. His fastball is still *good*, and it may be helping him hold his BABIP down in the .220s, but this does not, at first glance, look like a sustainable trend – particularly not since it was over .300 last year. For all of his velocity and elite spin rates, Kopech’s fastball continues to underperform. It’s not just the walks; he gives up lots of hard-hit contact, too.

Logan Gilbert and George Kirby are fine with hard-hit contact, and a part of me still thinks they could become Cy Young winners once they learn better breaking stuff to limit it. But their fastballs are so, so good that it doesn’t matter. Luis Castillo, Kirby, and Gilbert are all in the top 30 in MLB in Fastball run values (linear weights after each pitch) – it’s a counting stat, so the fact that Kirby’s that high despite having pitched 30-50 innings fewer than his competition says something. They give up hard line drives, but don’t walk many, and get swings and misses. Kopech’s done this before, but he is absolutely not doing it now.

Does this say that velocity isn’t important? No, I wouldn’t go that far. I still think spin is a bit overrated, and Kopech is showing why. But more than that, if you can’t control contact, then you simply have to control the zone. Giving up some smashed singles is fine for Logan Gilbert. It’s less good if you’ve walked two in the inning.

1: Juliooo, CF
2: France, 1B
3: Haniger, DH
4: Suarez, 3B
5: Winker, LF
6: Frazier, 2B
7: Trammell, RF
8: Casali, C
9: Crawford, SS
SP: Castillo

The Rays face Boston at home, while Toronto continues its series with erstwhile Wild Card rivals Baltimore.