A Dominating Quartet of Young Starting Pitchers

The top 12 of the last 30 day starting pitcher strikeout rate leaders is littered with the usual names. But of course as with any metric over an arbitrary time frame, there are a few surprising ones. Let’s discuss the four, who all happen to be 25 and under.

So I kind of knew that German Marquez was on some sort of a roll, but given that he calls Coors Field home, I didn’t bother to pay attention or dive deeper into his advanced metrics. Oops. It absolutely shocks me to learn that he has struck out a whopping 33.7% of the batters he has faced over the last 30 days. That rate ranks fifth among qualified starters! Not only has he been featuring strikeout stuff, he has also been displaying sterling control, holding a sub-6% walk rate. These strong skills have resulted in a 2.62 SIERA, a level you rarely see from a Rockies starter.

His last 30 days comprises his last six starts. A look at his velocity doesn’t yield any difference. However, a peek at his pitch mix does. He has thrown his fastball 10% less often, almost entirely exchanging those four-seamers for his slider. Why is that a good idea? Because it has been his whiffiest pitch this year, generating a superb 19.6% SwStk%. As we seem to see often, pitcher reduces fastball usage in favor of more deadly breaking pitch, strikeout rate surges. Seems so easy! I still always remain leery of Rockies pitchers, but Marquez, armed with big fastball velocity, looks like what we hoped Jon Gray would be.

I’m sure you noticed, but if not, Tyler Glasnow is good now. His last 30 days nearly comprises his entire time with the Rays, and if I remember correctly, he’s been used as part of their “opener and relievers” plan early on after his arrival. Perhaps surprisingly given his skills surge, his pitch selection and velocity have remained identical to his time with the Pirates. The big difference is an improvement in what has plagued Glasnow up until now — control. His strike percentage with the Pirates was a sad 59.4% (league average is around 63%), but it has spiked to 63% with the Rays. That’s still nothing special, but when a guy whose control was terrifying suddenly becomes league average, and already possesses big strikeout potential, that’s the recipe for a major breakout.

I should also note that Glasnow has become a fly ball pitcher with the Rays. I haven’t dug into pitch locations, but I’m guessing this was a concerted effort to throw higher in the zone for even more strikeouts. Though I prefer pitchers pitching in the NL than AL, I’m buying here.

Jack Flaherty has been rather dominant all year, so there’s nothing special about this particular stretch. His 13.3% SwStk% supports the over 30% strikeout rate, which itself is supported by a wicked slider, which has induced a 23.5% SwStk%. He also sports two other non-fastballs with double digit SwStk% marks, so he owns a true four pitch mix (fix if you separate the four-seamer from the sinker). For as long as he continues throwing that slider at least 30% of the time, he’ll keep something close to this up (though ERA in low-to-mid 3.00s, not sub-3.00).

Walker Buehler has been up and down with the Dodgers, but this last 30 day period he has turned it up a notch with the strikeouts. His velocity hasn’t moved, but he has ratcheted up the usage of his four-seamer at the expense of his sinker and essentially ditched his changeup. Four-seamers are preferable to sinkers for strikeouts, and Buehler’s owns an 11.2% SwStk% mark, which is elite for that pitch. His changeup deserved to disappear from his arsenal, as it generated a laughable 1.8% SwStk%.

However, what does worry me about Buehler is the fact that he doesn’t really have a standout pitch, aside from the four-seamer. Only two of his pitches have generated double digit SwStk% marks, the other of which is his cutter. But a 13.5% SwStk% as your best whiff pitch just isn’t very good. So far, Bueheler has managed such a strong strikeout rate because lots of foul strikes and an above average rate of called strikes. It’s not necessarily unsustainable doing it this way, but I like to see a high strikeout rate driven by more swinging strikes. As a result, he’s possibly the least intriguing of the bunch, though factoring in Coors means he’s likely above Marquez.