However, one candidate you can probably cross off is Blake Swihart. The Sox sent the catcher back to Triple-A Pawtucket on April 15, and he has increased his versatility there, playing left field on a part-time basis.
At this point, the Red Sox think it would be counterproductive to bring Swihart back to Boston for less than regular playing time.
"Yeah, he's got to keep playing," Farrell said of Swihart. "He's got to keep swinging the bat, too. He's taking on a new position, so that's going to take added concentration on the defensive side. I know he swung the bat a little bit better last night, so that's still got to come from him."
The reason the Red Sox have been going with 13 pitchers is that their starters haven't pitched deep in games consistently enough.
"We're at a point where we're kind of going day by day in terms of if the need for an additional arm is there still," said Farrell. "The goal will be to get back to four bench players. We'll look to go day by day through the weekend, and I would anticipate an adjustment as we get into Kansas City."
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him
on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.