The Red Sox optioned Criswell to Triple-A Worcester on Saturday.
Criswell fired seven innings of one-run ball Friday against the Astros, but he'll end up as the roster casualty necessary to make room for Dustin May in Boston's rotation. Criswell sports a 3.57 ERA through 17.2 innings with the Red Sox this season and would likely be the next man up if any of Boston's starters need to miss time down the stretch.