Over a span of three days, the 30-year-old righthander learned a new slider grip from pitching coach Andrew Bailey and refined his curveball.
He took the mound against the Kansas City Royals on Sunday a different pitcher than the one who lost to the Rangers.
The new guy was pretty good. Giolito allowed one run on two hits over 6⅔ innings as the Sox came away with a 3-1 victory before a crowd of 25,785 at Kauffman Stadium.
“Today was a big step forward,” Giolito said.
As it was for the Red Sox, who took two of three games from the Royals, cooling down the hottest team in baseball.
The Sox have won four of five. Their road trip continues in Detroit on Monday night.
“We had outstanding pitching all three games,” third baseman Alex Bregman said. “We showed we can win different kinds of games.
“The way Lucas pitched, what he did with the secondary pitches made everything else better.”
For a pitcher, trying to get away with just a fastball and changeup is like walking a tightrope. Eventually you’re going to wobble.
“As a hitter, you just sit middle and react to the pitch,” Sox manager Alex Cora said.
Mix in two effective breaking balls and now the hitter is off-balance. Giolito averaged 94 miles per hour with 43 fastballs and blended in 19 sliders, 17 changeups, and 9 curveballs.
Giolito credited Bailey and bullpen coach Chris Holt with his reinvention, which was a mix of physical adjustments and better pitch selection.
“Oh, yeah,” said Giolito when asked if this was something he can take into his next start and beyond. “I’m going to continue to make improvements.”
Giolito’s only trouble came in the third inning. Drew Waters singled and Luke Maile drew a walk. When Kyle Isbel bunted, Giolito made an errant throw to third and a run scored.
He left both runners stranded and ended his outing retiring 13 of 14.
It was Giolito’s best start since Sept. 15, 2023, when he pitched seven shutout innings against the Rangers while a member of the Guardians.
With the Sox down, 1-0, Wilyer Abreu hit a 430-foot home run to right field off Kansas City starter Seth Lugo in the fourth inning. It was his team-leading 10th of the season, five fewer than he had over 132 games last year.
Jarren Duran singled off Lugo in the sixth inning ahead of a 440-foot blast to center field by Rafael Devers. It was his seventh.
It was the longest home run of the season for the Sox.
Devers was 2 for 3 with an intentional walk. He has reached base safely in eight of his last nine plate appearances, shrugging off the controversy about his refusal to play first base.
Justin Wilson, Greg Weissert, and Aroldis Chapman followed Giolito to the mound. It was the sixth save for Chapman, but not an easy one.
Second baseman David Hamilton committed an error with one out in the ninth. Salvador Perez then singled, bringing the winning run to the plate.
Maikel Garcia hit a low liner to left field that Duran made a sliding catch on. Chapman threw Mark Canha five consecutive fastballs between 99-100.3 m.p.h. The final one produced a foul pop that first baseman Nick Sogard handled.
The Royals had won seven straight and 10 of 11 before dropping the final two games of the series.
Peter Abraham can be reached at peter.abraham@globe.com. Follow him @PeteAbe.
