Aaron Cook dropped to 3-7 on Tuesday (AP)

On a night when Aaron Cook allowed five runs in five innings in a 5-3 loss to the Angels, he wasn’t the only Red Sox starter in action. Left-hander Felix Doubront tossed five simulated innings in the bullpen, and he appears set to come off the 15-day disabled list. Right-hander Daisuke Matsuzaka, meanwhile, threw seven shutout innings for Triple-A Pawtucket in which he permitted one hit, walked four and struck out seven. In five starts during his current rehab assignment, he has a 2.78 ERA.

Cook actually had pretty sharp stuff. He got nine groundball outs along with a season-high four strikeouts, but he was done in largely by a number of well-placed grounders (he gave up 11 hits, but of those, nine were singles, with most sneaking through holes in the infield). He did make one horrific pitch, a belt-high fastball over the plate that Mark Trumbo sent to another zip code for a two-run homer.

Still, in his last five starts, Cook is now 1-4 with a 6.92 ERA; on the year, he’s 3-7 with a 4.94 mark. And so, at a time when his results have been substandard, there is a reasonable chance that Cook will be removed from the rotation. The veteran insisted that the subject does not prey on him, and that he has given it “not one bit” of his attention.

“It’s not my decision,” said Cook. “I’m just going to take the ball and throw when they tell me. Whatever happens happens.”

Manager Bobby Valentine suggested that he was not yet ready to say whether or not Cook would stay on turn for another start.

Much too early to figure that one out,” said Valentine. “We’ll see what … watch the film tomorrow, see Dice, see how he feels. Talk it over with everyone.”

Of course, one of the parties has already talked with the team. Doubront said that he would make his next start on Sunday — five days from now, on what would seemingly be Cook’s turn in the rotation. Thus, it would appear that the possibilities for the team are either adding Doubront in place of Cook to preserve a five-man rotation, adding Doubront and keeping Cook in the rotation for a six-man turn (it’s worth noting that the Sox started a stretch of 16 games in 16 days on Tuesday) or adding Doubront and Matsuzaka while removing Cook for a six-man rotation.

Either way, it appears that change is imminent in a Red Sox rotation that has been the team’s foremost weakness all year.