Masterson might be headed to bullpen

ATLANTA -- After making a fourth rehab outing on Tuesday night, Justin Masterson should be ready to return to Boston's roster by the end of the week. However, there are currently no spots available in the starting rotation.

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This could lead to Masterson working out of the bullpen, where he does have some experience.

"I think he's proved he's ready to come back," said manager John Farrell. "It depends on what role we put him in."

And what will that depend on?

"The remaining guys on our roster and certainly our pitching staff. We haven't ruled out the possibility of that being in the bullpen," said Farrell. "That's not to say that decision is made, but we've got probably another four days until he's ready to take the ball and compete at this level just by normal rest."

In his final rehab start, Masterson gave up four hits and two runs (one earned) over six innings. He walked three and struck out four.

The righty has long expressed a preference for starting, but he struggled before his DL stint, going 2-2 with a 6.37 ERA.

Farrell has spoken to Masterson about the possibility of being a reliever.

"He understands this decision isn't about one person," Farrell said. "What's best for us is the direction we'll take at that time."