No less than four times during his pregame session today with reporters, manager John Farrell said the Red Sox' decision to demote Alfredo Aceves to Triple-A Pawtucket was "performance-based," not related to the right-hander's tendency to be a distraction.

"Performance-based, solely," Farrell said. "Not just in the outings this year, but going back last six weeks, eight weeks last year, this was strictly performance-based."

Aceves allowed eight runs in only 3-1/3 innings Wednesday night against the Oakland Athletics. He has an 8.66 ERA in five appearances (three starts) this season and an 8.51 ERA in his last 25 starts dating to the beginning of last August.

But Aceves also has been enigmatic off the mound. He was suspended for three games last year after slamming the door to manager Bobby Valentine's office, then got into a shouting match with second baseman Dustin Pedroia during a game in Oakland. In spring training, Aceves irritated Farrell by lobbing the ball to home plate in a live batting practice drill.

"The issues or occurrences that you're referring to were dealt with individually at the time," Farrell said. "This was performance-based."

Aceves has previously stated his preference to start, although the Red Sox still view him primarily as a swing man who can pitch multiple innings out of the bullpen and enter the rotation in the event of an injury.

"The good outcomes for Alfredo and the Red Sox are when he's pitching better and he's effective," GM Ben Cherington said. "That's what we're all focused on right now. We'll continue to do whatever we can to help him get there. Ultimately, it's going to be up to him."

Farrell said Aceves took the news of his demotion "like a pro." Aceves will be used as a starter in Pawtucket.