The Red Sox identified an issue with Whitlock's (elbow) changeup, and the pitcher has been able to work on it during his rehab, Christopher Smith of MassLive.com reports.

EDGE Analysis

Whitlock's changeup was a big pitch for him during his rookie 2021 season. The offering averaged 83.1 mph and opponents went 10-for-54 (.185) with one home run and one double against it. This year, the pitch is averaging 84.9 mph and opponents are 8-for-20 (.400) with two home runs and three doubles. "We noticed [the increased velocity] in Milwaukee before [the injury]. We were talking about it. And we were able to make adjustments. Obviously he had time to work on it. And he felt really, really good about the changeup in the last [rehab start]." Whitlock will make his final rehab start Sunday and is expected to slot back into Boston's rotation this coming weekend against the Diamondbacks.