BOSTON -- Following Tuesday night's 5-3 loss to the Oakland Athletics, prospect Lars Anderson was optioned back to Triple-A Pawtucket.
However, the Red Sox won't make a corresponding roster move until Wednesday.
There are a few unknowns regarding the roster, which is why the team will wait.
Still unclear is what will happen to veteran right-hander Aaron Cook, who is in the process of letting the Red Sox know if he wants to exercise his Tuesday opt-out clause.
If the Red Sox are at risk of losing Cook, they might add him to the 25-man roster and put him in the bullpen.
Cook was solid in four starts at Triple-A Pawtucket, but Boston doesn't have any vacancies in the starting rotation.
Should Cook decide not to exercise his opt-out clause, he can go back to Pawtucket for one more month. The righty has a second opt-out clause on June 1.
One more thing clouding the roster is the uncertain status of third baseman Kevin Youkilis, who has missed the past three games with back stiffness.
"Again, he's doing everything he can do," said manager Bobby Valentine. "He's got a situation. I don't know how to address it, whether it goes away quickly or if he needs a lot of time for it to go away. I'm just trying to get the advice of those who are working on him."
To cover themselves for the short term, the Sox did call up shortstop Jose Iglesias prior to Tuesday's game, but by sending down Junichi Tazawa, they were left with an 11-man pitching staff. Typically, the Red Sox have a 12-man staff.
If Youkilis is going to be out for an extended period, the Red Sox could opt to call up top prospect Will Middlebrooks. The third baseman has had a red-hot start to the season.
Or they could move Mike Aviles over to third base and play Iglesias at short.
Anderson's latest stint with the Red Sox was uneventful. He was 1-for-8 in six games.