Can this free-agent starter reinvent himself -- again?

December 20th, 2023

This year's free-agent class offers no shortage of quality starting pitching.

Even with , , and (who won't pitch in 2024) off the board, there are plenty of strong starters remaining. Japanese phenom , reigning NL Cy Young Award winner and 2023 World Series champion still haven't found new homes. There's one available starter, though, who isn't far removed from pitching like one of the best starters in baseball.

had the unfortunate timing of producing down years in his final two seasons before free agency, with things going a bit off the rails in 2023. The long-time White Sox starter was traded to the Angels at the Deadline and then plucked off waivers a month later by the Guardians. In total, Giolito had a 4.88 ERA -- 3.79 with Chicago and 6.96 with his other two teams -- and allowed 41 home runs in 184 1/3 innings.

After pitching like a frontline starter from 2019-21 (3.47 ERA and 11.3 WAR in 72 starts), is it possible for Giolito to reinvent himself like he did earlier in his career? Let's find out.

Giolito's transformation into frontline starter

The Nationals selected Giolito 16th overall in the 2012 Draft out of Los Angeles’ Harvard-Westlake High School, the baseball factory that also produced , and .

Giolito underwent Tommy John surgery shortly after signing with the Nats, which pushed his MLB timeline back to 2016. The right-hander struggled in his first cup of coffee (6.75 ERA in six games) before he was included in the trade that also sent and to the White Sox for .

After producing a 2.38 ERA -- albeit with iffy peripheral numbers -- in seven starts for the White Sox in 2017, Giolito had a 6.13 ERA and 5.26 expected ERA in 32 starts for the White Sox in '18. His ERA and 0.1 WAR (FanGraphs version) were the worst among 58 qualified starters.

Just as doubts crept in about Giolito's viability as an MLB starter, he broke out in a dominant 2019 season. In an inflated offensive environment that saw an MLB single-season record 6,776 home runs, Giolito posted a 3.41 ERA (134 ERA+), punched out 228 hitters in 29 starts, was a first-time All-Star and finished sixth in AL Cy Young Award voting.

Giolito continued his run of success in the shortened 2020 season with a 3.48 ERA and 2.0 WAR in a dozen starts while tossing a no-hitter and finishing top-10 in Cy Young Award voting once again. When he produced a 3.53 ERA with 4.1 WAR in 31 starts in 2021, Giolito was firmly established as one of the top starters in the game.

When examining what changed for Giolito, an obvious starting point is acknowledging that he was a talented pitcher who just needed to work through his early-career struggles. That isn't nearly enough to account for all of his transformation, though. Giolito made significant changes across the board, including his arm slot, fastball velocity, pitch mix, and overall command of his stuff.

As James Fegan documented for The Athletic in 2019 (subscription required), Giolito tinkered with his arm slot in his tough 2018 season and then made wholesale changes during the 2018-19 offseason. The most obvious and well-known change was drastically shortening his arm action, which led to more deception and unlocked added velocity that showed up in 2019.

Giolito's 92.4 mph average fastball velocity in 2018 placed him in the 42nd percentile. A year later, Giolito's fastball jumped to 94.2 mph, putting him in the 67th percentile of pitchers. Giolito also scrapped his previously ineffective sinker, which allowed him to focus on elevating his faster four-seamers up in the zone. The results were obvious, as Giolito saw his expected wOBA against fastballs go from .392 in 2018 to .289 in '19.

It wasn't just the fastball that saw big changes. Whereas Giolito threw five pitches at least 10% of the time in 2018, he simplified his pitch mix to his four-seamer, changeup and slider, which accounted for 95.9% of his pitches in 2019. Giolito boosted his changeup usage to 26.2% in 2019 after it hovered around 15% for the first three seasons and he threw his four-seamer a career-high 55% of the time.

“This year I’ve been much more of a three-pitch pitcher, and at times, a two-pitch pitcher,” Giolito told Fegan at the end of the 2019 season.

Giolito also improved his command after walking an MLB-high 90 batters in 2018. That figure dropped to 57 in 2019, while Giolito shaved his walk rate by 3.5%. A big part of that came down to improving his first-pitch strike rate by nearly 7%. Heading into 2022, Giolito looked poised to continue producing like one of the top starters in the sport.

Explaining Giolito's struggles from 2022-23

All signs indicated that Giolito would continue his success into his final two years before he could reach free agency. Based on his production and trajectory, Giolito was lining himself up for a huge payday after the 2023 season.

Except, Giolito saw his numbers decline across the board.

Giolito from 2019-21 vs. 2022-23
ERA: 3.47 vs. 4.89
FIP: 3.54 vs. 4.70
K rate: 30.7% vs. 26.3%
Whiff rate: 33.1% vs. 28.6%

Whether it was raw ERA or his underlying numbers, Giolito went from a frontline starter to an innings-eating backend starter on short notice. That it came in his age 27 and 28 seasons made it all the more confounding. Just as there were obvious reasons for his early-career transformation, it's easy to spot what went wrong from 2022-23.

As the numbers above indicate, Giolito went from an elite strikeout pitcher to merely a good one. From 2020 to ’23, his percentile ranks in both strikeout rate (92nd to 67th percentile) and whiff rate (94th to 70th percentile) plunged.

That drop in strikeouts can mostly be explained by a fastball that lost its effectiveness. In that stretch of three-year dominance, Giolito was comfortably above average in terms of fastball velocity and spin. That was not the case from 2022-23 when Giolito saw his velocity and spin rate drop below the 40th percentile in each season. As a result, hitters posted an .848 OPS against Giolito's four-seamer in the last two years.

The decline in Giolito's fastball also resulted in a less effective changeup and slider. Opposing hitters slugged just .368 against Giolito's changeup, slider and oft-used curveball from 2019-21. In the last two seasons, hitters slugged a healthy .450 against those same pitches.

Because Giolito was generating fewer whiffs and allowing more quality contact, he allowed a career-high 41 home runs in 2023 that trailed only 's 44 home runs.

Can Giolito reinvent himself for a second time?

In a revealing interview with FanGraphs' David Laurila, Giolito talked about how he can get back on track for next season. Surprisingly, Giolito's top reason was surprisingly simple: executing his pitches better.

“I think the issue has mostly been lack of execution," Giolito told Laurila. "When I was really effective, I would pound the zone with the changeup. I would throw it for a strike pretty much whenever I wanted. I’ve found that when I’m not having success, my fastball command is off, and I’ll also throw too many changeups that aren’t competitive. I’ll throw them in the dirt or high out of the zone.”

That gets to the crux of Giolito's issues since 2022. While Giolito has lost roughly a tick on his fastball velocity, there don't appear to be other major red flags in terms of pure stuff, velocity and movement. It might be as simple as executing and commanding his pitches like he did from 2019-21.

Maybe Giolito won't quite return to his previous levels but there might be a middle ground between his peak years and last two seasons. We've seen other starters -- such as likely future Hall of Famers , , and -- navigate declines in fastball velocity to maintain high levels of success.

Giolito has never been on the level of those pitchers but he's pitched at a high enough level to make him a candidate to work with declined velocity. As Giolito also told Laurila, the right-hander thinks his stuff is mostly intact and that trying to "consistently command my fastball to the top of the zone" could help make the entire arsenal more effective.

The other piece of this puzzle is Giolito finding a landing spot that could help him attempt to return to previous success. Plenty of teams who are in the Yamamoto market -- such as the Dodgers, Yankees, Mets, Giants and Phillies -- will need a fallback option if the right-hander signs elsewhere. Giolito might not bring the same value as Yamamoto but he could be a strong secondary option for teams with demonstrated track records of pitching success.

Maybe Giolito is what he is at this point: an innings-eating No. 4 or 5 starter who can reliably provide league-average innings for a team. That's still valuable, but there's enough history and recent success for teams to think they can squeeze more out of Giolito. If Giolito can find himself pitching closer to his 2019-21 levels, he might end up being one of the top signings this offseason.