About last night: Logan Gilbert has gone underground

We joke sometimes on the site about Logan Gilbert as a “mad scientist” because of his penchant for exploration and experimentation, but truthfully, it’s a gift to be able to cover someone who not only possesses Gilbert’s talent, but also his scholar’s curiosity about his craft, as well as his analytical approach towards implementing changes. Some experiments are more successful than others, but Gilbert is never stagnant; even as a young pitcher, he has a keen understanding of the game’s ability to pass one by for those that might rest on their laurels. Since he set foot in the big leagues, Gilbert has constantly sought improvement; last night, he showed we might be seeing the best version of him yet.

The general caveat of “it was against the A’s” applies, but Logan Gilbert had one of the best starts of his young career last night: he only needed 77 pitches to clear eight innings, striking out six and walking none, and he was a hung curveball away from shutting out the A’s over those innings. If the entire fortunes of the 2023 Mariners weren’t currently balancing on the head of the pin that is rotation health, we might have seen Gilbert complete his first-ever complete game at the big-league level, which is a feat no matter what opponent it comes against. Alas, but a fine pitching performance nonetheless.

All night, Gilbert toyed with the A’s, matching their aggression with aggression of his own—he was still registering his four-seamer at 97 mph at the end of his outing, but had been working all game with an uptick in fastball velocity. Gilbert’s been averaging around 95 mph on his four-seamer this year, but last night bumped his average to 96.3 mph. That’s exactly what his fastball averaged in his last outing, when he held a powerful Braves lineup to two runs over six innings of work, striking out nine. For contrast, 96.5 mph was the hardest fastball Gilbert threw against the Tigers back on May 14, when he gave up three runs over 5.2 innings and struck out just four while throwing three wild pitches, needing 94 pitches to grind through his outing. But here’s “Walter” blowing a cool 97.2 past Jace Peterson to open his eighth inning of work:

Gilbert has always described himself as a fastball-first pitcher, which makes sense: with his elite extension and plus velocity, his fastball theoretically should be his best pitch. But MLB hitters haven’t whiffed at the pitch often—only around 21% of the time—and about half the time are able to make hard contact when they do impact the baseball. With his fastball living in the upper part of the zone, hitters will rarely put it on the ground; the hope is for them to make weak contact, pop it up or maybe fly out, or to earn a whiff. Sometimes that doesn’t work out, and those well-meaning fastballs leak into the middle of the plate and wind up deposited over the fence.

But two pitches this season are helping Gilbert get the ball on the ground more often, and in doing so, are allowing his fastball to play up: the slider and the new splitter. Gilbert’s ground ball rate has risen to 42.7%, a career high, largely thanks to a change in slider shape and introducing the splitter to replace his old changeup.

Here’s how Gilbert’s slider has changed shape from 2022 to 2023, so far.

So far this season, he’s getting the slider onto the edges more and avoiding the heart of the plate with it. It’s sweeping less and dropping more, and has transformed from a change-of-pace pitch (run value of 0 last season) to a true weapon (run value of -5 so far this season). That’s making the pitch pair better with his curveball, which has similar movement, and making both pitches play up. Gilbert’s slider now splits the plate, avoiding the middle like poison, and when he’s really got it going he can break it away from righties and lefties alike. Here he is striking out the hottest hitter in baseball, Ronald Acuña Jr., with a perfectly-placed hard slider:

Ah darn it, this piece was supposed to be about ground balls. Okay, here he is getting a ground ball on a pitch even further off the plate to a righty off the slider, which he now gets 60% ground balls off of rather than 45%:

Gilbert has been brutally honest about his changeup, which he scrapped this off-season due to its ineffectiveness. When he threw the pitch, it generally got good results because batters either weren’t expecting it or didn’t know where it was going. Unfortunately, Gilbert also didn’t really know where his changeup was going:

This year he’s replaced that pitch with the splitter, which he’s able to locate more consistently, and which also lands in good spots for grounders, especially for lefty batters to reach out and make weak contact against.

Gilbert threw his splitter and slider a lot against Atlanta, mixing it with his four-seam to keep the Braves hitters guessing. Against the A’s, he led with his four-seam, challenging the aggressive A’s hitters, but he also mixed in a healthy dose of his slider and the splitter. The A’s had some ugly swings against both last night, some of which went for nice ground ball outs and others that got A’s hitters into bad counts or resulted in strikeouts like this:

But while the splitter generated strikeouts, the fastball generated ground ball outs at a higher rate than usual—not a trend that’s likely to continue, but a good adjustment to a team desperate to hack at the fastball to try to create solid contact. Knowing the A’s were trying to avoid seeing the slider or splitter allowed Gilbert to ramp up usage of his fastball, answering aggression with aggression, throwing it harder and in more advantageous counts to generate strikeouts and easy groundouts.

Gilbert is famously a tinkerer, always trying to find a new way to level up and become a better version of himself. But something seems to have shifted for him lately; he’s innovating because he wants to, not because he feels like he has to in order to stay in the league.

“I feel comfortable with who I am, as a person, as a pitcher, and feel like things don’t shake me as much,” said Gilbert postgame. “I’m not really questioning who I am or if I belong. . .I feel really confident out there.”

Gilbert credited the Mariners’ mental skills coaches and also his catchers and the game they call for helping the galaxy-brained Gilbert focus on one pitch at a time and be able to “flush” bad results in favor of good process and staying competitive in the zone. The analytically-minded Gilbert might have a good grasp of game theory, but he’s definitely not one to fall prey to the gambler’s fallacy.

“Just try and get the ball in play and if they hit it, they hit it,” he said, shrugging. “You know, if you roll the dice like that, more often than not, you’ll be all right.”