Crosby has signed with the Red Sox, Matt Eddy of Baseball America reports.

Crosby has spent most of the past seven years in the Tigers' minor league program, and has struggled with injuries throughout his career. Even if he can stay healthy with Boston, he will likely spend the majority of the 2015 season in the minors, limiting any fantasy value.

Crosby was released by the Tigers on Monday, Chris Iott of MLive.com reports.

In order to open up a 40-man roster spot, the Tigers have opted to jettison the 25-year-old left-hander. The move is warranted, as Crosby posted an unsightly 5.71 ERA, 1.637 WHIP, and 12:13 K:BB in 17.1 innings (11 outings) at Triple-A Toledo this season.

Casey Crosby (triceps) close to returning to game action.

It had been reported that the young southpaw was dealing with elbow soreness, but it was actually an inflamed triceps that caused him to miss time. He came into camp expected to compete for a spot in the Tigers bullpen.

Casey Crosby (elbow) will throw a live batting practice session on Friday.

Crosby started feeling elbow soreness a week ago, but he's progressing and could be cleared for game action soon. The southpaw is competing for a spot in the Tigers' bullpen.

Casey Crosby (elbow) threw a successful 25-pitch bullpen session on Sunday.

Nursing some elbow discomfort and inflammation in his triceps, Crosby will have to throw at least one more bullpen session before being allow to face hitters and eventually getting into a Grapefruit League game. The left-hander is making a transition from starter to reliever this spring and isn't expected to make the Opening Day roster.

Casey Crosby (elbow) has been shut down for a few days due to discomfort in his left elbow.

The 25-year-old is expected to compete for a spot in the Tigers bullpen this spring. He'll be re-evaluated in a couple of days before determining a course of action.

Casey Crosby will compete for a job in the Tigers' bullpen during spring training.

All 93 of Crosby's appearances between the minors and majors have come as a starter, but the Tigers have decided to shift him to a relief role. It's a move that's probably overdue, as Crosby has a big arm but has struggled to throw strikes throughout his pro career. With Ian Krol and Phil Coke already locked into relief roles, Crosby will surely begin 2014 at Triple-A. In time, he could develop into a bullpen weapon.

Tigers general manager Dave Dombrowski said Monday that Casey Crosby will likely be shifted to the bullpen.

It makes sense, as Crosby had an ugly 4.84 ERA and 61/40 K/BB ratio over 57 2/3 innings in Triple-A this season while missing time with a shoulder impingement. His control has been a major issue as a starter, but he could be more effective in smaller doses out of the pen.

Tigers prospect left-hander Casey Crosby was placed on the 7-day disabled list with Triple-A due to a left shoulder impingement.

Crosby felt some soreness during his recent start and will now get some extended rest. The 24-year-old southpaw has really struggled this season, posting an ugly 5.30 ERA and 39/28 K/BB ratio in 37 1/3 innings through eight starts.

Tigers optioned LHP Casey Crosby to Triple-A Toledo.

Crosby could be the team's "No. 6" starter if they wind up trading Rick Porcello. For now, the left-hander will continue working on his control at Triple-A.

Casey Crosby is not available Saturday due to a foot infection.

It's not anything to be concerned about. Crosby is expected to start the season as depth at the Triple-A level for the Tigers, but should see time in the majors at some point in 2013.

Tigers pitching coach Jeff Jones told Lynn Henning of the Detroit News that they expect Casey Crosby to have a good spring training and a great season now that he's older and more experienced.

The 24-year-old left-hander, and fifth round pick from the 2007 draft, struggled in his brief audition with the Tigers in 2012, posting a 9.49 ERA and 2.10 WHIP over three starts. He'll start the season as depth at the Triple-A level, but is likely to see time in the Tigers rotation at some point in the 2013 campaign.

Tigers optioned LHP Casey Crosby to Triple-A Toledo.

Crosby was sent down after giving up four runs over 3 2/3 innings Friday night against the Rockies. The 23-year-old southpaw had an ugly 9.49 ERA and 9/11 K/BB ratio over his first three big league starts. While he remains an intriguing prospect, he's not ready for prime time. Jacob Turner is a possibility to replace him in the starting rotation.

The Tigers are considering skipping Casey Crosby in the rotation due to Monday's off-day.

"I'm not sure about that," manager Jim Leyland said. "I'm thinking about that one." Leyland didn't alter his rotation during the Tigers' last off-day, but may skip Crosby to allow Justin Verlander to pitch on normal rest. Verlander will either start Thursday against the Cubs or Friday at home against the Rockies, depending on which way Leyland wants to go with the rotation.

Casey Crosby picked up his first major league victory after allowing three runs in 5 1/3 innings Thursday against the Indians.

Crosby allowed five hits, walked three and struck out two, so he was far from dominant in lowering his ERA to 9.35 today. He's likely to make at least one more start before Doug Fister returns.

Tigers recalled LHP Casey Crosby from Triple-A Toledo.

He'll get the start Friday against the Yankees, taking the rotation spot of the injured Doug Fister. Crosby, 23, has a 4.26 ERA and 57/26 K/BB ratio in 50 2/3 innings over his first nine starts at the Triple-A level this year. While he holds some long-term intrigue, he's not a recommended fantasy play against the Bronx Bombers.

Tigers optioned LHP Casey Crosby to Triple-A Toledo.

Crosby allowed six hits and four runs in 5 2/3 innings this spring in the Grapefruit League. The 23-year-old southpaw will join the Toledo starting rotation.

Tigers purchased the contract of LHP Casey Crosby from Double-A Erie.

Crosby at least stayed healthy in 2011 after an injury-shortened 2010 campaign, but he posted a pedestrian 4.10 ERA and 1.51 WHIP while striking out 121 over 131 2/3 innings for Erie. Still the southpaw has a great arm, and the Tigers weren't going to expose his upside in the Rule 5 draft.

Battling back from injuries, big league Casey Crosby is ready to pick up where he left off in 2009.

Although most of last year was lost to injury, Crosby dominated Single-A West Michigan in 2009, finishing 10-4 with a 2.41 ERA. Despite adopting a more efficient throwing motion, he still throws at 97 MPH and possesses an arsenal of three effective pitches. "Surgery might have been a blessing in disguise," Crosby said. "It made me take a break, get some things right mechanically that I was doing wrong." Now healthy, he remains one of the organization's top minor league prospects.

Tigers pitching prospect Casey Crosby has a tender pitching elbow and likely won't make his first scheduled start of the season.

The 21-year-old left-hander will undergo an exam to make sure there is no structural damage in the elbow. Crosby previously underwent Tommy John surgery in November of 2007, but returned to go 10-4 with a 2.41 ERA and a 117/48 K/BB ratio in 104 innings for Class A West Michigan last season. He was recently ranked as the organization's No. 2 prospect by Baseball America.