The Red Sox made the announcement early Monday evening. Dr. James Andrews will perform the surgery.
"He's got a chronic UCL injury that we were trying to manage conservatively," said Red Sox general manager Ben Cherington. "Symptoms did increase the last few days, so we talked more amongst the group and with Carl late last week, over the weekend, Carl wanted to give us through the weekend, play in the Yankees series. We agreed to circle up on it today, and we've decided to get it taken care of."
The reason Crawford's 2012 season started late was due to left wrist surgery, which he underwent in January. But while he was coming back from that injury, Crawford started to experience discomfort in his left elbow, particularly while throwing.
"It's tough, being a pitcher and knowing what that ligament means to your elbow and how you feel on a day-to-day basis I couldn't imagine doing what he's been doing," said Red Sox lefty Jon Lester. "It seems like any time we need a big throw or a guy stretching a single into a double it's always hit to him. This will be good for him for peace of mind -- get everything right and get back next year and know that he doesn't have to worry about anything and just play baseball."
Initially, Crawford and the Red Sox took a conservative approach and tried to avoid surgery. But as the weeks went by, Crawford's elbow didn't get better.
Activated by the Red Sox on July 16, Crawford actually swung the bat far better than he did in his first season in Boston. In 31 games, he hit .282 with 10 doubles, three homers, 19 RBIs and five stolen bases.
"I think it became clear over the last few days that surgery was going to happen, it was just a question of when," Cherington said. "We felt like after talking about it more this weekend and with Carl, the right thing to do was to get it taken care of now. Give Carl credit. He played through the injury and played pretty well. But the symptoms, it wasn't getting better. The symptoms were getting worse. We just decided not to ask him to keep going out there. We decided to take care of it now and he agreed with that."
With 40 games left in the season, the Red Sox trail the Yankees by 13 1/2 games in the American League East, and Boston entered Monday's off-day a season-high 7 1/2 games back in the AL Wild Card standings.
If Crawford played through the injury for the final six weeks of 2012, there would have been no chance for him to start the '13 season on the active roster. Cherington estimated that a position player can return from Tommy John surgery within seven to nine months.
"When it takes you longer to get ready to play a game than it does to actually play the game, something is wrong, and I think that's where Carl was," said Red Sox right-hander Josh Beckett. "It's frustrating. I know he definitely wasn't excited about the meeting he had today. He wants to go out and play. He tried to get some things done."
Crawford had said in recent weeks that Dr. Andrews had told him surgery was all but certain to be needed at some point. In the end, however, Cherington said the Red Sox made the decision.
"The [team's] medical staff ultimately make the recommendation, but there's other people involved," Cherington said. "We did consult Dr. Andrews again recently just to fill him in on the way it's been and what Carl has gone through more recently and, ultimately, the medical staff, factoring in all the information including the recent increase in symptoms, and we made a recommendation that it's probably something that needs to get done, and it's just a question of when it gets done. We felt like the time was now."
With Crawford two seasons into a seven-year, $142 million contract, the Red Sox would obviously like to get as much as possible from him going forward.
"He's got a UCL injury, and it's pretty clear -- everyone knows that and he's been playing on it," Cherington said. "This is a long-term contract -- he's here for a long time -- so we've got to be sure that we're doing the right thing for him and ultimately for the team, too. This is not a short-term investment."
Crawford's final at-bat of the season was Sunday night against the Yankees, as he hit a single to left in Boston's 4-1 loss.
"Carl's given it everything he has," manager Bobby Valentine said Sunday night.
Boston has some depth in the outfield to withstand the loss of Crawford. Scott Podsednik has done a solid job when called on. Daniel Nava has been on the disabled list with a left wrist injury, but he could be back soon. Ryan Kalish has struggled in two stints at the Major League level this season, but he is still an option.
"It's going to be hard to fill his shoes. Even when Carl is only playing 75 percent of what he's capable of playing, it's still better than most people," said Red Sox right-hander Clay Buchholz. "It's going to be a tough loss. He's been dealing with it and tried to find a way to battle through it. Seeing him in the clubhouse every day, knowing that he just wants to go out and do what he can on the field every night, it's tough to watch. Hopefully, he gets a full recovery."
Injuries have been a never-ending theme for the 2012 Red Sox. Crawford's DL stint will mark the 30th served by 26 different Boston players this season.
"The biggest thing for us is to have him 100 percent healthy," said Red Sox first baseman Adrian Gonzalez. "We know the kind of player that he can be, the kind of impact he can have on a game. We've got guys that can step in, but he is definitely a big part of our success. We saw what he's capable of doing by the time he was playing."