Lucas Giolito's Rise from MLB's Worst Pitcher to Its Best

Up until recently, arguably the most interesting things about Chicago White Sox right-hander Lucas Giolito were his family ties to TV classics like Seinfeld and Twin Peaks.
But that was then. This is now, when it's hard to spot a better pitcher in Major League Baseball.
Giolito went into May with a 5.30 ERA through his first four appearances of 2019. That was at least better than his career ERA to that point, but only by 0.16 points.
Then the 24-year-old went off for a 1.74 ERA over six starts. As a result, Major League Baseball deemed him the American League's Pitcher of the Month.
Evidently not content to stop there, Giolito has celebrated the arrival of June with 15 shutout innings in his first two starts. He now has a 1.28 ERA with 66 strikeouts, 12 walks and only 32 hits allowed in his last eight starts.
"I'm just happy that it's happening for him and for us," White Sox manager Rick Renteria said Saturday, according to Robert Falkoff of MLB.com. "He's a young man that we had high hopes and expectations for when he was acquired. His outings have been fantastic. I think he is showing that he is part of some of the best pitchers in the major leagues at this moment."
If anything, Giolito may be the best pitcher in the majors right now. According to FanGraphs wins above replacement, no pitcher has outperformed him since he began his run on May 2:
- 1. Lucas Giolito, CHW: 2.7 WAR
- 2. Chris Sale, BOS: 2.2 WAR
- 3. Max Scherzer, WAS: 2.0 WAR
As personified by these numbers, the Giolito of 2019 bears little resemblance to the Giolito of 2018. The latter was allowed to make 32 starts despite putting up a 6.13 ERA, which is the 12th highest in history among pitchers who've started at least 30 games in a season.
A year like that will prompt a guy to reassess some things. To his credit, Giolito has done exactly that and remade himself into a completely different pitcher.

Giolito's father, Rick, and mother, Lindsay Frost, are both actors. So was his late grandfather, Warren Frost. His uncle, Mark Frost, is a novelist who's best known for co-creating Twin Peaks with David Lynch.
But rather than travel down a path to show business, Giolito found himself on one to professional baseball once he sprouted into a 6'6" drink of water with a live-wire right arm. He was plucked out of Harvard-Westlake High School by the Washington Nationals in the first round of the 2012 draft, and he was the top pitching prospect in baseball just four years later.
"The sky is the limit for Giolito, who has the stuff, physicality and command to develop into an ace," read one section of his MLB.com profile for 2016.
But then weird things started to happen. Giolito hit some walls at the upper levels of the minors in 2016, and his first taste of the majors was a flop punctuated by a 6.75 ERA over six appearances. There wasn't a huge outcry when the Nationals dealt him to the White Sox in December 2016.
Giolito struggled to reclaim his lost hype in 2017, and his 2018 disaster seemed to kill it altogether. It wasn't just his ERA that was ugly. He also led the AL by issuing 90 walks, and he mixed in only 125 strikeouts over 173.1 innings.
However, Giolito did find something with his changeup midway through 2018. It suddenly picked up more horizontal movement and, accordingly, took on a larger role in his pitch mix. Opposing batters hit just .156 against it after July 8.
Giolito's changeup now accounts for 24.2 percent of his pitches, and that figure is only going up.
This approach has worked especially well against left-handed batters, who've gone from a .271 average against Giolito in 2018 to only a .165 average in 2019. Right-handed batters are also seeing more changeups from Giolito, however, and their average against him has fallen from .227 to .194.
Righty batters also have to contend with Giolito's slider, which has held them to a .057 average. It's hard to blame them for that. As illustrated by Rob Friedman, here's what they're up against:
According to the man himself, however, a more important change occurred during the 2018-19 offseason when he decided to overhaul his pitching motion.
"Just more compact, athletic," Giolito said of his new delivery, per Jay Cohen of the Associated Press. "Arm action's shorter, so less time for error. So like when my front foot strikes the ground and the power and the weight transfers, my arm is in a more ready-to-fire position than it has been in the past."
The difference isn't difficult to spot. This was Giolito just before and just at the moment his left foot hit the ground in 2018:

And this is him in 2019:

Giolito's control has benefited, as he's improved from 4.7 walks per nine innings in 2018 to only 2.6 this season. So has his fastball velocity, which has risen from an average of 92.4 mph to 94.0 mph.
The shape, so to speak, of Giolito's heat is also different. He featured a sinker in 2018, only to have it knocked around to the tune of a .274 average and .445 slugging percentage. He's now throwing only four-seamers, which are yielding a .216 average and .299 slugging percentage.
As Giolito explained to James Fegan of The Athletic, however, the most important benefit of his new delivery is the deception it's added to his pitching style:
"I'm hiding the ball better behind my body when I'm in my motion, where I used to (miming his older, long throwing motion) show the ball to the hitter, show the ball to the hitter, then bring it up and throw it, they can really time off of that. Now I load and I'm hiding it behind my body and they're not seeing it until I'm up in the firing position. That can probably help with disrupting timing as well."
Above all, this explains the newfound dominance within the strike zone. His rate of contact in the zone was formerly well above average. Now it's decidedly below average, as is his overall contact rate.
Even when hitters do make contact against Giolito these days, it tends to be not with a bang but with a whimper. His soft-hit rate is on the rise, and his 86.3 mph average exit velocity since May 2 ranks 12th among qualified pitchers.
At this point, Giolito basically doesn't have anything he needs to do better. In light of how recently he needed to do everything better, that's no small feat.
Chances are his honors for this season won't stop at the AL Pitcher of the Month for May. From here, his first All-Star selection and even the AL Cy Young Award are very much in play.
Stats courtesy of Baseball Reference, FanGraphs, Baseball Savant and Brooks Baseball.