The Red Sox optioned reliever Zack Kelly to Triple-A Worcester on Tuesday in order to activate starter Brayan Bello for his season debut.

Kelly entered the season with a 3.95 career ERA over career games between his ‘22 debut and the end of last year. This season, he’s again shown flashes of brilliance but struggled to be consistent. In seven appearances he allowed 10 runs, all earned, on 12 hits. He’s issued two walks, hit two batters, and struck out 11 men in 10 innings.

The right-hander, 30, is one of the hardest-throwers on the staff, with his fastball velocity in the 77th MLB percentile. On the Red Sox, only Garrett Whitlock (79th) and Aroldis Chapman (98th) outrank him. However, though it’s a small sample size, Kelly is also getting hit much harder than in the past: a 46.7% hard-hit rate, compared to 31.7% over the first three years of his big-league career.

“The way that went, it wasn’t the right way,” Cora said of the most recent outing on Sunday. Kelly gave up a single and hit back-to-back batters to load the bases without recording an out,  and Justin Wilson allowed all three runners to score.

“I think it’s consistency,” the Sox skipper continued. “Like, one good outing in a week, is that good enough? Well, it helps, but we know there’s more there. We do know that. Like, this guy can be a back-end reliever on a championship-caliber team, we just have to get there.”

While Cora praised Kelly for throwing first-pitch strikes, he noted that the right-hander needed to do so consistently. He also posited that Kelly might be trying to do “too much.”

“To get three outs, we’re trying to use every weapon instead of just being on the attack and get people out,” he said.

With a healthier pitching staff and a high payroll, the margin for error is smaller than in year’s past. Since early in spring training, Cora has stressed the importance of executing. He did so again in discussing Kelly on Tuesday.

“The whole thing about projections and all that, we have to turn the page and we have to execute,” Cora said, “and he knows that.”