“It feels like it’s coming around,” Severino said. “The fastball is there, breaking pitches, too. I feel like I’m on the right track.”

The next step for him will be a simulated game at the Yankees’ minor league complex in Tampa, followed by an appearance with one of the team’s minor league affiliates.

Barring any setback, the Yankees will have a healthy and fully-restored Severino for the final month of the season. That would be no small addition for a rotation that has lacked a bona fide ace since Opening Day. Any chance that C.C. Sabathia could have filled that void were dashed by his wobbly performance against the Indians on Sunday: he allowed four runs in three innings, giving Cleveland enough of a cushion to survive the Yankees’ two-run rally in the bottom of the ninth.

Although most of the Yankee Stadium crowd had already cleared out, those fans who remained were excited by the possibility of a comeback: the Yankees were within four runs, had runners on second and third with one out and Didi Gregorius and Gio Urshela, their Nos. 3 and 4 hitters, coming to the plate. But the rally turned out to be nothing more than a tease. Brad Hand, a lefty, struck out Gregorius on three pitches and got Urshela to line out to left to end the game.

The close call served only to underscore how the Yankees had been sabotaged by Sabathia’s rustiness. Nursing an arthritic knee, he was making his first start in nearly three weeks and admitted he was disappointed with his effort, especially the three-run home run he allowed Mike Freeman.

“I really hung it up there,” Sabathia said of his slider. “I’ve been doing that a lot this year, especially to left-handed hitters. I have to tighten that up.”

Despite the vow, Sabathia has no illusions of turning back the clock. His E.R.A. stands at 5.01 and he says his knee remains as troublesome as ever. Even with the extended stay on the injured list and a platelet rich plasma injection, Sabathia admitted his pain-level, on a scale of one to 10, “was about an eight” during Sunday’s game. “Eight is as good as it’s going to get,” he said, for the rest of the season.