Balfour was added to the 25-man roster before Saturday night's game, which meant a spot had to be cleared, and the Rays opted to option right-hander Shawn Camp to Triple-A Durham.
Camp appeared surprised by the move.
"Obviously, the last two games I haven't thrown too well," Camp said. "The thing about baseball is it's what have you done for me lately. It's like one of those situations where you walk into a dark room and don't know where the light switch is. That's how I feel."
Camp has been with the Rays all season and has an 0-3 record with a 7.20 ERA in 50 appearances.
"This organization's been good to me," Camp said. "They've given me multiple opportunities to be successful this year. I think the important thing is to assess what's going on with me now and get it fixed. My sinker's just been inconsistent. Second half, I really turned it on last year. It would have been nice to get off to a real good start in the second half, and I thought I was on that pace until I ran into the last two games, it's been really rocky."
Camp believes a lot of the problem rests between his ears.
"I think for me, a lot of it has to do with confidence right now," Camp said. "I think, in situations I've been pitching in, you really have to pitch with a lot of conviction to get the job done. I haven't shown that as of late."
Despite his struggles this season, Camp said, in his mind, he's a Major League pitcher and feels like he belongs in the Major Leagues.
"But that's obviously not the direction the organization is going at this moment," Camp said. "It's out of my hands now. All I can do is go wherever I'm going and pitch. If it's with Tampa Bay in the future, that would be wonderful, there's a lot of opportunity here."
Camp said Rays manager Joe Maddon told him he could be back in two weeks or not at all.
"That's totally their decision," Camp said.
Complicating matters for Camp is the fact his wife, Heidi, is pregnant with the couple's first child.
"I really think the most important thing right now is my family," Camp said. "The birth of my child is in two weeks. That's something I have to really take into consideration. I hate the fact it's happened this way because I have to move my wife. But unfortunately, that's the business I'm in."
Camp said the thought of not reporting to Durham did not even enter his mind.
"No, I wouldn't do that," Camp said. "You have to be a man in a situation like this. I'm not going to be a child. They have obviously given me ample opportunity to succeed."
Maddon said anytime he has to send out a player it's a difficult day for a manager.
"And Camper's such a popular guy around here," Maddon said. "We were able to option him down there. He's going to pitch. It doesn't mean he's out of the plan for the future. We just want to try to get him back on track, see how it works out. The second half of last season he was a very productive member of this staff; we just couldn't seem to get him into any kind of consistent groove this year. But that's not saying he can't."
Balfour arrives: The new addition to the 'pen, Balfour arrived shortly before batting practice Saturday night and said he wasn't too surprised about getting traded.
"I knew they had to make a move when they traded for [Scott] Linebrink," Balfour said. "It's one of those things where the guys in [Milwaukee's bullpen], they've been there all year and they've done well. I kind of figured something was up. I had no idea it was this."
Balfour thinks his new locale brings a great opportunity.
"I spoke to my father last night in Australia. I said look at Detroit a couple of years ago and look where they're at," said Balfour, who hails from New South Wales, Australia. "People telling you you're going from a winning team [to a losing team]. It can turn around quick."
Balfour showed well in 24 games this season for Triple-A Nashville, where he was 1-1 with five saves and a 1.69 ERA. He wasn't as successful with the Brewers, going 0-2 with a 20.25 ERA in three relief appearances.
"I got away from what I was doing in Nashville," said Balfour. "I was attacking the hitters all year long. I was very successful there. Then I went to Milwaukee and began to nit-pick. I tried to do too much. ... You learn your lesson in a couple of games. Now, I can come here and relax and know what I need to get back to."
Maddon noted that Balfour's numbers were "spectacular" at the Minor League level this year and pointed out Balfour is a strike thrower and called that "interesting."
Crawford sore: Carl Crawford was not in Saturday night's starting lineup. The left fielder's right wrist was sore in the aftermath of a diving attempt to make a catch in Friday night's game.
"He's a little bit sore," Maddon said.
Crawford felt some pain swinging the bat, but he was available for pinch-running or late-inning defense Saturday night.
Crawford will receive treatment and the decision on whether he will start Sunday will wait until Sunday.
Up next: The Rays will wrap up their three-game series against the Red Sox on Sunday afternoon in a 1:40 ET contest at Tropicana Field. Left-hander Scott Kazmir will start for the Rays and will be opposed by right-hander Daisuke Matsuzaka.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.