Cook's spot in the rotation comes up on Saturday, but Valentine opted to put left-hander Franklin Morales in that position and push Cook back a few days. Valentine said he doesn't necessarily plan on using a six-man rotation going forward, but he wants it to be flexible.
"The plan is to have a plan that is adjustable right now as needed," Valentine said. "[After Doubront returns], the six might stay at six or it might become five again depending on what we see. Right now, a little blow for Felix is what the doctor ordered. [He needs to] take a deep breath ... and I think he'll have that other gear that we saw him have earlier in the season."
Doubront, who is in his first full season at the big league level, has begun showing signs of fatigue with his high number of innings pitched. The left-hander currently sits at 122 2/3 frames on the season, more than he's thrown at any level since 2008, when he recorded 129 1/3 innings for Double-A Portland.
On Thursday night, Doubront cruised into the fifth inning with a 3-1 lead. But he had little control of his fastball in the fifth. Doubront allowed three runs in the frame before exiting with only one out. He has now allowed a combined seven runs n the fifth innings of his last two outings. Doubront is 10-6 with a 4.70 ERA in 22 starts.
Valentine said nearly every pitcher starts to hit a wall at this point in the year.
"Guys either bust through the wall or you give him a little breather," he said.
With Cook's start still a few days off and the bullpen overworked, Valentine said he could be available in relief Friday night.