The Red Sox optioned Weber to Triple-A Pawtucket after Friday's 11-2 loss to the Orioles.
The right-hander will cede his spot on the active roster to Nathan Eovaldi (elbow), who was reinstated from the 60-day injured list in a corresponding move. Weber has made three starts for Boston this season, but he worked exclusively in relief during his latest stint with the big club, giving up four runs (three earned) in 4.2 innings over his two appearances.