The Red Sox optioned Lars Anderson back to Pawtucket after the game. General manager Ben Cherington did not say what the corresponding move was. But now the Sox have a spot open for righthander Aaron Cook, who is 3-0 with a 1.89 earned run average in five starts for Pawtucket.

On Tuesday, Cook had the right to opt out of his contract if the Red Sox did not promote him to the major leagues. The Sox then had 48 hours to promote him, release him, or make other arrangements.

Talking it over

Clay Buchholz has an 8.69 ERA and a 1.90 WHIP through five starts. His latest uneven performance, which came against Oakland Monday, led to a meeting with Valentine before the game on Tuesday.

“There’s no doubt he has plenty of room for improvement,’’ Valentine said. “I’m not sure he’s totally comfortable with all his pitches.

“He’s had games where he’s really liked his two-seamer; really liked his curveball; really liked his changeup at different times. But they haven’t been a total package the entire time.’’

Valentine said Buchholz was the most relaxed he has seen him all season during their meeting.

“I think that’s a good sign,’’ the manager said.

According to Valentine, the Red Sox feel Buchholz is throwing the ball better than his statistics would indicate.

“They should correlate because they’re pretty good pitches,’’ he said. “Not a lot of other arms in the league are featuring the pitches that he’s featuring.’’

Buchholz allowed six runs on seven hits and five walks against Oakland Monday, improving to 3-1 despite giving up five runs in the seventh inning.

“He really liked the way the ball was coming out of the hand,’’ Valentine said. “So did [pitching coach] Bob McClure and so did I the majority of the time [Monday] night. The idea that he can improve is absolutely paramount in all our minds.’’

Game rescheduled