Is Gavin Williams an Ace for Real?

ZiPS has been generally one of the most positive projection systems in recent years regarding the Cleveland Guardians, but it has not been quite as excited about them when it comes to the postseason. The reason? Throughout the 2020s, their rotation has typically been thoroughly competent, but not very top-heavy, and the sprint of the playoffs is a different beast than the marathon of the regular season.

This season, Cleveland is hovering around the .500 mark, but that’s no fault of the starting pitching, where there’s an argument that it has now developed two aces, an ingredient that’s an important part of a recipe for making a deep postseason run. One is Parker Messick, who previously dominated in the upper minors and seemingly didn’t need an adjustment period when he debuted with the Guardians last August. He’s emerged as one of the top pitchers in the AL, and he’ll almost definitely get downballot Cy Young votes this season. Gavin Williams, on the other hand took a bit longer to really arrive in the majors, but I think he’s unambiguously there now.

A first-round pick in 2021, Williams boasted an impressive prospect pedigree as he advanced quickly through the Guardians system. He debuted in June 2023, and although he didn’t provide the same immediate impact that Messick did, Williams performed rather well in his rookie season (3.29 ERA, 4.05 FIP, 1.1 WAR in 82 innings) and has generally been an adequate mid-rotation starter despite some issues with elbow soreness in 2024. Even so, across his first three seasons, Williams hadn’t quite emerged as a true frontline starter. He was striking out a batter an inning, but that’s not as impressive a feat as it was 30 years ago, and besides, his raw stuff suggested the potential for more.

Now, finally, we’re witnessing Williams’ breakthrough. His 3.78 ERA is actually higher than last year’s mark of 3.06, but I’d argue his success has been more sustainable. Williams’ solid FIP (3.67) in 2024 was kept low by a hard-to-maintain home run percentage, and last year’s ERA was aided immensely by an even-harder-to-sustain .254 BABIP, while his FIP in 2025 inflated to 4.39. In 2026, there are no such illusions. Williams has allowed more home runs than you’d like, but he’s knocked a third off his walk rate (from 11.8% in 2025 to 7.9% this season) while simultaneously improving his strikeout rate by a similar margin (33.3%, up from 24.6% last year).

This kind of improvement is significant, as walks and strikeouts are two of the most stable stats for pitchers. One thing I calculate for myself occasionally is a K%/BB% improvement score, which looks at the rate of improvement in both percentages, and adds them together. Yes, this is mathematical violence for reasons we won’t get into, but I’m just trying to get a rough ranking, so it gets the job done. I’m using the 500 pitchers with 120 innings in consecutive seasons. By this simple method, the year-on-year improvement for Williams is the fifth largest of the last decade.

The foundational basis for this improvement is strong. Williams’ contact rate is the fourth best in baseball of the 93 pitchers with at least 120 innings, and his out-of-zone contact rate, the most important part of contact rate, ranks third, behind only Jacob Misiorowski and Jacob deGrom. His out-of-zone swing rate is easily the best of his career. His first-pitch-strike percentage is also at a career high, and a big improvement over last year, when he led the league in walks. This is an important leading indicator of future walk rate, and it significantly improves our predictive ability beyond simply knowing his current walk rate.

Williams is simply far more of a pitcher than a thrower than he’s ever been before. His usage of his pitches has changed significantly from previous seasons. He’s canned his changeup, a lesser part of his arsenal in 2023-2024, and he’s still very strong with the platoon disadvantage despite lacking a traditional offspeed pitch. He’s taken a similar approach to Kevin Gausman, who largely makes up for his uninspiring breaking pitch by utilizing his splitter as if it were a slider. Williams has changed how he approaches lefties, and is now far more confident about throwing sinkers and sliders/sweepers to them, even in two-strike counts. After throwing sinkers and sweepers to lefties only 10% of the time in 2025, that usage has more than tripled, to 33% in 2026. Sweepers/sliders have gone from 9% against lefties in two-strike counts to basically being in parity with his fastball and curveball, at 29% this year. Jack Foley at PitcherList wrote about Williams’ arsenal changes a couple months ago, so I’ll just provide the link for further reading.

This is intentional on his part. Williams drastically curtailed his use of his four-seamer in June while he reworked his approach a bit, with his four-seamer rate dropping all the way down to around 10%.

“I was being more rotational than what I wanted,” Williams said earlier this week in Detroit. “I call it a more north-south delivery approach. So it helps out with the angle of the heater and helps move the ride on the heater.”

In the linked article above, Jared Greenspan included the change in Williams’ heat maps. I’ve updated it through mid-September.

That’s a much tighter control of his fastball, and you can see the change in the results. He’s gone from a hard-hit rate of 48% and an average exit velocity of 91.8 mph before June to 41% and 88.9 mph since, fueling a slugging percentage drop from .403 to .265.

Naturally, this has changed the long-term outlook in the projections for Williams. ZiPS already liked Williams enough in the preseason to rank him 14th among pitchers in projected 2027-31 WAR, at 12.5 and wedged between Logan Gilbert and Max Fried. Now, he’s up to eighth and getting into rarefied air.

If the projections are correct, and if the Guardians do not make Williams fabulously wealthy soon via an extension, somebody else will when he becomes a free agent after the 2029 season.

Back in the 2010s, one of the Guardians’ strengths was their starting pitching, with five different pitchers putting up five-WAR seasons (Corey Kluber, Shane Bieber, Carlos Carrasco, Trevor Bauer, and Justin Masterson). They’ve yet to have anyone accomplish that feat in the 2020s. Now, with Messick (who may squeeze it out this year) and Williams, Cleveland once again has at least two pitchers who could put up Cy Young-worthy numbers. Gavin Williams is turning his raw stuff into polished domination, and the two aces give the Guardians a good chance at punching above their weight should they make it into October.