It's Official: Bailey Will Have Surgery
Pete Abraham on Boston.com:
And:
It was determined that Andrew should undergo surgery to reconstruct the ulnar collateral ligament in his right thumb. The surgery is scheduled to be performed by Dr. Graham tomorrow in Cleveland.
Jarrod Saltamacchia had that surgery near the end of the 2010 season. The surgery typically takes 3-4 months of recovery time. Given that Bailey is a pitcher, it could be longer given that he would need time to rebuild his arm strength and regain his command.