The right-hander had a long conversation with Francona and the medical staff Wednesday and it was decided it would be best for Beckett to refrain from throwing for the next 10 days. Beckett has been on the disabled list since May 19.
During a side session last Friday, pitching coach John Farrell noticed inconsistencies in Beckett's delivery, so the session was stopped. Francona said Beckett started to feel discomfort in his lat muscle.
"We lean on this guy too much, so until we can completely get him to where he's going through his delivery, we're going to make him take it easy," Francona said Wednesday. "He understands it, he doesn't love it, but he realizes this is in his best interest, which ends up being in our best interest. We're going to be pretty firm on this one."
Beckett dealt with a similar injury much of the 2008 season and pitched through the discomfort, which led to arm and oblique issues.
Joe McDonald covers the Red Sox and Bruins for ESPNBoston.com. Follow him on Twitter.