Lucas Giolito Changed His Delivery, And Pitchers Around MLB Are Following His Lead


Since the start of the 2019 season, Lucas Giolito has been one of the best pitchers in all of Major League Baseball. In 284.2 innings of work, he has pitched to a stellar 3.57 ERA and 3.46 fielding-independent pitching mark, and he ranks eighth during that span among pitchers in FanGraphs’ wins above replacement with 7.5. So it’s easy to forget that, just a year before his string of dominance began, he was a far cry from the pitcher we know today.

In 2018, Giolito struggled to miss bats and find the strike zone with consistency, as evidenced by his 16.1 percent strikeout rate and 11.6 percent walk rate. (The major league averages for strikeout and walk rates that year were 22.3 percent and 8.5 percent, respectively.) Of all of the pitchers who qualified for the ERA title,1 Giolito was actually baseball’s least valuable pitcher, pitching to a 6.13 ERA and 5.56 FIP — just a shade above replacement level. Though Giolito had been a highly regarded prospect, selected out of high school by the Washington Nationals with the 16th overall pick in the 2012 draft, it had been such an abysmal year that he knew he needed to make changes if he was going to be a successful major leaguer.

But between the 2018 and 2019 seasons, Giolito saw a dramatic shift in performance. His strikeout rate more than doubled to 32.3 percent (and has hovered around the 30s ever since), and his walk rate plummeted to 8.1 percent. Giolito’s seemingly overnight success was no fluke, though — the tools were there all along. Rather, it was a slight mechanical change that unlocked his potential — a change that seems to be sweeping the rest of baseball as well.

To start, take a look at the last pitch Giolito threw in 2018.

And compare that to his first pitch of 2019.

Before 2019, Giolito’s arm swing was longer, extending far behind him before coming up to his release point. After he made the adjustment, his arm went from his glove to his release point in a shorter, more intentional path. This shorter arm path, which is more common with infielders, is generally not taught to youth pitchers because it goes against the old wisdom of “reaching back and firing.” But the shorter action seems to be exactly what Giolito needed.

Both Giolito’s adjustment and results thereafter caught the attention of analysts, coaches and fellow players. Numerous other pitchers have adopted the same shorter release, including Brandon Woodruff of the Brewers, Jordan Hicks of the Cardinals, Joe Musgrove of the Padres and Shane Bieber of the Indians, just to name a few. Here are those four before they made the Giolito Adjustment.

Baseball Savant

And here they all are afterward. While not all of them have made as drastic a change as Giolito did, there are still clear changes in the arm motions.

Baseball Savant

This type of arm action isn’t new, but there is something to all of these pitchers making a similar tweak in their deliveries in a similar time frame. 

“I am the type of guy where I take the ball out of my glove pretty late, and when I take it out early, it feels super weird.” Giolito told baseball analyst Rob Friedman in an August 2020 interview. “So I decided, ‘Why don’t we just shorten the arm action altogether?’ … quicker and up to the ear.” Giolito said the Driveline Baseball program and its PlyoCare balls, along with several different throwing drills, helped him train his new arm path.

Hitters notably rely on timing to maintain repeatability in their mechanics, and so do pitchers. In that same interview, Giolito said shortening his delivery helps him to be “on time” when making a pitch — getting his arm into the optimal position when his front foot strikes the ground. When this timing is off, pitchers may have trouble finding the strike zone, as Giolito once did. But bigger problems can also occur: Their arms may lag behind, causing them to leak kinetic energy and lose velocity, and they could compensate by drawing energy from elsewhere, risking serious injury. 

To both maximize velocity and reduce the risk of injury, pitchers need to get their arm into what is known as “the high cock position” at front-foot strike. Once this happens, they create the torque needed to throw the ball with elite speed. Driveline calls this “positive disconnection.”

Baseball Savant

Notice that in the second photo, after he made the adjustment, Giolito’s arm is more cocked, as opposed to before the adjustment, when it was farther from his body and dragging behind. Since making this change, Giolito has thrown more strikes, prevented more runs and added velocity to his fastball. The adjustment, small as it was, made his mechanics better, which made his pitch arsenal better, which made his results better.

Lucas Giolito has been a different pitcher

Metrics for Lucas Giolito in 2016-18 vs. 2019-21, including ERA, fielding-independent pitching (FIP) and called plus swinging strike rate (CSW%)

Pre-adjustment Post-adjustment Diff.
Innings 240.0 284.2 +44.2
ERA 5.48 3.57 -1.91
FIP 5.68 3.46 -2.22
Avg. fastball velocity 92.5 94.1 +1.6
Avg. fastball spin rate 2,072 2,348 +276
CSW% 24.9% 31.2% +6.3

Through games of May 9, 2021.

Sources: FanGraphs, Baseball Savant

In 2020, Giolito threw his first no-hitter — twirling a 101-pitch, 13-strikeout gem against the Pittsburgh Pirates in an empty stadium. In both 2019 and 2020, he received down-ballot Cy Young Award votes. This season hasn’t gone quite as well yet: Though FanGraphs projected Giolito to be the most valuable pitcher in 2021, his run prevention hasn’t lived up to the expectation, thanks in large part to a rough outing in Boston in which he allowed seven earned runs in just one inning of work. 

As for the other notable pitchers who have made the Giolito Adjustment, returns have been strong so far. Bieber won the American League Cy Young Award in 2020, a year after winning the 2019 All-Star Game Most Valuable Player. Musgrove threw the first no-hitter of the 2021 season. Woodruff, who has quietly become one of the best pitchers in the league, has increased his average fastball velocity to nearly 97 mph. Hicks opted out of 2020 while also rehabbing from Tommy John surgery, and he’s currently on the injured list with an inflamed elbow, but to start this season, he was pumping triple digits.

The adjustment isn’t a panacea — plenty of others with a similar arm angle have failed to win a Cy Young, and Giolito’s own struggles this season show that it isn’t the end-all, be-all. But Giolito’s transformation, and the success of the players who have made similar adjustments after him, means that more and more pitchers are likely to make these changes. That includes pitchers who want to streamline their deliveries, pitchers with injury histories, and pitchers who have already succeeded at the major league level and are trying to unlock a little something extra. It’s not as if pitchers needed another magic bullet to throw harder, add spin, increase movement or generally get better results in game, but they may have just that.

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