CLEVELAND -- If there were an American League Cy Young Award just for the second half of the season, Cal Quantrill would have a convincing case to take home some hardware.

Quantrill’s torrid late-season stretch continued through the Indians’ 4-1 victory over the Royals on Tuesday at Progressive Field with yet another one-run outing on seven hits and two walks with six strikeouts through 6 2/3 innings. It marked the 10th time he’s given up one or zero earned runs in his 13 starts since the All-Star break.

“He’s turned into a starter and is doing the things to prepare each time he goes out,” Indians acting manager DeMarlo Hale said. “That’s good to see.”

The Indians were trying to learn what they had in Quantrill during last year’s abbreviated season after acquiring him at the Trade Deadline. Because of their crowded starting rotation, he was immediately put in the bullpen and attempted to prove he could make a bigger impact as a starter this past spring. But Cleveland stayed with what it knew best, leaning on Shane Bieber, Aaron Civale, Zach Plesac, Triston McKenzie (who impressed late in 2020) and Logan Allen, who had such a hot spring that he was impossible to ignore.

Quantrill, again, was headed to the bullpen, but after shaky starts from McKenzie and Allen at the beginning of the year and injuries to Bieber, Civale and Plesac, Quantrill quickly became the hurler who couldn’t be ignored.

Quantrill was thrown into the rotation out of desperation, as the club was looking for any arm that could eat up multiple innings during some of its biggest struggles toward the end of June. But the transition was far from a smooth one for Quantrill, who owned a 5.46 ERA while allowing a .277 average and a .796 OPS to opposing hitters through his first six starts as a member of the rotation (June 16-July 10).

“I think if you look back when he came out of the bullpen and he became a starter and started to build his pitch count out,” Hale said. “But more importantly, I think his body is getting used to that.”

It wasn’t until Quantrill had a brief breather during the All-Star break that he suddenly found a second gear.

Quantrill entered his start Tuesday with an American League-leading 1.79 ERA in his 13 starts since the Midsummer Classic. Only Max Scherzer (1.27) has a lower second-half ERA across the Majors. And after Quantrill’s latest one-run performance, that ERA lowered to 1.76.

“You know what, he’s just pitching the baseball very well,” Hale said. “He’s mixing his repertoire. He’s attacking hitters differently. … He’s almost like not trying to do too much but staying in his rhythm.”

Quantrill has leaned heavily on his sinker and slider all season, though since the All-Star break, his slider has been his most-used pitch (33.2%, up from 26.4% in his first six starts since joining the rotation). The slider had held hitters to a .188 average entering Tuesday, while the sinker held hitters to just a .176 average in the first 12 starts after the All-Star Game.

Quantrill’s success with the slider trickled into Tuesday’s outing, as he induced five whiffs, improving his whiff rate to 28.7% since the All-Star break, which is an improvement from his 26.9% whiff rate from his first six starts in the rotation. And although he hasn’t used his other three pitches (four-seamer, curveball and changeup) as frequently as he did before the break, he’s since mastered the timing of when to turn to each, as Hale often credits his improved pitch sequencing.

“I felt like we had to work a little bit to get the changeup and curveball where I wanted them,” Quantrill said of his outing on Tuesday, “but by the end of the game, I felt like we had all four [pitches in the slider, sinker, changeup and curveball].”

Of all pitchers who have made at least 13 second-half starts, Quantrill’s 1.76 ERA is the lowest, topping American League Cy Young candidate Robbie Ray’s 2.21 ERA in that span. He may not have had enough time in the rotation to get into this groove earlier in the season, but Quantrill is giving the Indians a lot of hope for the depth of their rotation in 2022.

“That’s kind of growing into a pro, as I call it,” Hale said, “where you start to understand what it takes if you’re going to be a starter: Your daily routine and then [you’re] prepared when your time has come. That’s growing into a pro.”