Buchholz suffered the injury while running the bases in San Francisco on June 26. Half of Boston's six All-Stars won't play, as second baseman Dustin Pedroia (fractured navicular bone, left foot) and catcher Victor Martinez (left thumb fracture) are also on the disabled list.
The good news is that Buchholz's injury is not serious and he should be back during the first time around the rotation following the All-Star break. Lefty Felix Doubront was called up from Triple-A Pawtucket to take Buchholz's spot on the roster and will make his second Major League start on Tuesday night against the Rays.
"We just weren't comfortable with the running part," said manager Terry Francona. "When he was trying to run, he was still feeling it. There was no reason for us to rush into it, so we just kind of kept letting it go and seeing if he did get better, but there was no way we were going to let this kid pitch unless he was perfect."
Though Buchholz would have loved to pitch this weekend in Toronto -- not to mention the All-Star Game -- he was ultimately on the same page with the Red Sox regarding the decision.
"I said to him, I don't know if it was yesterday or the day before, 'Flip it around. What would you do?' He said, 'Probably DL me.' We can DL him, he can get his work done and then coming out of the break, we can just pitch him early on," said Francona. "It kind of builds into a break and helps us come out of the break also."
Buchholz is still looking forward to going to Anaheim and taking part in all the festivities that go along with being an All-Star.
He will lean on returning All-Stars David Ortiz, Martinez and Pedroia for guidance on how to handle the experience, as well as perhaps Kevin Youkilis if the first baseman wins the AL's Final Vote competition.
"I'll probably be piggybacking them, walking around, following them the whole time," Buchholz said. "I'm looking forward to it."
And the Red Sox look forward to Buchholz (10-4, 2.45 ERA) reclaiming his spot in the rotation after the break.
Yankees left-hander Andy Pettitte, who was the next on the player vote list, replaced Buchholz.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.