Logan Gilbert’s Secret Weapon

With just a week until the All-Star break, the Mariners have played their way into the thick of the AL Wild Card race, though our Playoff Odds remain skeptical. Based on their pre-season projections, you might expect their surprising success to be linked to two of their top prospects having made their debuts in mid-May. You’d be partially right. While Jarred Kelenic’s big league career hit a major hiccup, Logan Gilbert has been a solid addition to the Mariners’ beleaguered starting rotation.

Gilbert has made nine starts in the majors so far and has compiled a 4.10 ERA backed by an impressive 3.50 FIP. In an ideal world, the Mariners probably would have liked to see Gilbert develop a bit longer in Triple-A earlier this season, but a bunch of injuries to their rotation forced their hand a bit. James Paxton, Nick Margevicius, and Ljay Newsome are all out for the season. Marco Gonzales missed time with a strained forearm. Justin Dunn has been sidelined recently with some recurring shoulder issues. Yusei Kikuchi has pitched extremely well, and deservedly earned the team’s only spot on the American League All-Star roster, but behind him, the rotation has been rather thin. Gilbert’s success at the highest level stabilized that group at a critical point as they began making their way up the standings. With just over 40 innings pitched under his belt, we now have an adequate amount of data to start comparing his minor-league scouting report to his major league results.

The foundation of Gilbert’s repertoire and approach lies in his four-seam fastball. His scouting report had his heater sitting 91–94 mph in the minors but he’s pushed that average velocity up to just under 95 mph in the majors. And that above-average velocity plays up even higher due to his elite release extension. When Devan Fink explored Bailey Falter’s effective velocity a couple of weeks ago, Gilbert was the only pitcher in baseball who had more release extension than Falter did. By adding over 2.5 mph of perceived velocity to his heater, Gilbert has the sixth hardest fastball thrown by a starting pitcher in the majors when sorted by effective velocity. In addition to that fantastic velo, Gilbert’s fastball also possesses excellent ride, sitting in the 83rd percentile among all four-seamers thrown at least 100 times.

That elite extension certainly seems like it would be the secret weapon mentioned in this article’s headline, but the results don’t really bear that out. His 22.5% whiff rate with his four-seamer is exactly league average for that pitch type and batters have had little trouble doing damage against the pitch when they put it in play. When you look at his pitch heat map for his fastball, you get a sense for why his results haven’t matched up with the elite raw characteristics on the pitch.

Despite possessing excellent command of his fastball throughout his minor league career, Gilbert has grooved far too many of his four-seamers in the majors. He has located 12.4% of his heaters middle-middle based on Baseball Savant’s attack zones, the 14th highest rate in baseball. Opposing batters have absolutely crushed those meatballs to the tune of a .656 wOBA. Throwing strikes regularly is a significant part of his approach, and it’s a big reason why he’s been able to keep his walk rates well below league average throughout his professional career. To reach his ceiling, he needs to find a way to show greater finesse with his fastball location or risk allowing far too much loud contact off those pitches in the middle of the zone.

No, Gilbert’s true secret weapon is a pitch that he only gained a feel for at the Mariners alternate site last year: his changeup. Back in March 2020, Gilbert talked to David Laurila about his pitch repertoire, and this is how he described his changeup:

“My change is a circle. There’s not much to it. It’s more of a location-based pitch that I try to keep low and away. The action is what it is. It’s not going to be a swing-and-miss pitch for me. At least not now.”

Eric Longenhagen put a 55 Future Value grade on it in Gilbert’s most recent scouting report, believing the pitch could show some late development. That’s exactly what happened at the alternate site last year. Gilbert studied the best changeups in the game and made adjustments to the pitch to find the best combination of feel and physical characteristics. In an interview with The Athletic’s Corey Brock last summer, Mariners pitching coordinator Max Wiener said, “[Gilbert has] been posting changeup actions that are unprecedented and are beyond our expectations.”

Gilbert didn’t throw a changeup in his debut start on May 13 and threw just four of them through his first four starts. But he’s slowly increased the usage of the pitch at the expense of his curveball.

He threw 16 changeups in his last start on July 2, the greatest number he’s thrown in a game thus far. And every single one he’s thrown this year has been to a left-handed batter.

What about the pitch itself? This is where things get really interesting. His changeup comes in at 78.8 mph on average, a 16 mph difference from his fastball. That’s the second largest velocity differential for any changeup thrown at least 50 times this year. And with all the additional perceived velocity his elite extension imparts on his fastball, that velocity differential is even higher. Gilbert has a similar amount of release extension on his changeup but the perceived velocity imparted on the slower pitch is less than what he adds to his fastball. Gilbert’s changeup also possesses a phenomenal amount of vertical movement. The pitch drops 40.4 inches on it’s way to the plate, the eighth highest amount of drop among that same sample of changeups as before.

Those two outstanding characteristics have combined to help Gilbert generate some incredible results with the pitch. Among all individual pitches thrown at least 50 times this season, the swinging strike rate on his changeup ranks fifth in the majors at 30.9%, one step below Patrick Sandoval’s elite changeup. On a per swing basis, the pitch’s whiff rate is a mind boggling 73.9%, easily the highest in the majors.

Here’s what the pitch looks like in practice:

That’s a perfectly placed changeup on the outside corner that Yoán Moncada can only flail at. Thrown with the same arm action, the pitch looks like a high fastball out of his hand but tumbles out of the zone and crosses the plate far later than expected. Here’s another one located down and in that brings Ji-Man Choi to his knees:

Mariners manager Scott Servais commented on the quality of Gilbert’s changeup during a recent radio interview.

“For me, the changeup has a chance to be lights-out and eventually I think he’s going to start throwing it to right-handed hitters, as well. Right now it’s pretty much just against the lefties, but when he starts mixing it against the righties as well, it’s really going to allow his fastball to play up even more.”

Adding another potentially plus pitch to his repertoire is critical because Gilbert has struggled with the consistency of his curveball. At one point during his minor-league career, his curveball was thought to be his best secondary offering, but it’s been a pretty ineffective pitch for him in the majors. He’s left far too many up in the zone and opposing batters just don’t seem to be fooled by the pitch. It’s possible that ineffectiveness is related to a drastically different release point for his big bender.

Gilbert’s curveball has come out of his hand much higher than the rest of his pitches. It’s possible that’s by design; he acknowledged as much in his interview with Laurila last year.

“My curveball doesn’t really tunnel well, but it’s so different that… it comes out of the hand really high, so hitters give up on it a lot. That’s why it’s better early in the count. I can bury it, too — that will come off a better sight line — but if I’m trying to land it for a strike, it comes out so high that hitters tend to kind of lean back a little bit.”

That kind of approach might have worked well in the minor leagues where batters might not be as prepared for such a big curveball, but it hasn’t worked in the majors yet. He might have to take that breaking ball back to the drawing board. As he’s picked up the usage of his changeup, Gilbert has started to fade the curveball; he’s thrown just 12 of them in his last four starts. But with a solid slider and his new changeup, he may not need the curveball at all. He can use his sweeping slider against right-handed batters and keep lefties at bay with the change. Paired with elevated fastballs, that up-and-down approach could be a recipe for success.

Gilbert has earned a reputation as a cerebral tinkerer who isn’t afraid to dig into the data to improve his pitches and approach. We’re witnessing that on-the-fly development this year at the big league level. His ability to take a pitch that was considered an afterthought in his repertoire and work it into a phenomenal weapon is a fantastic sign for his future.