The news is a setback for one of the more durable pitchers in baseball over the last decade; he's made at least 32 starts and has thrown for at least 199 innings in every season from 2005-13.
The 37-year-old, an All-Star in 2006, said he is determined to return and pitch for a few more years but admitted that he has pitched six starts this season with a torn UCL, MLB.com reporter Steve Gilbert tweeted. He had been hoping to rehab the injury in an effort to avoid surgery but an MRI in June confirmed that the UCL had completely come of the bone.
A date for the surgery has not been set but assuming it happens soon, a return for the second half of the 2015 season appears to be on schedule with a typical timetable for a return from Tommy John surgery.
Arroyo, currently in the first year of a two-year contract worth $23.5 million, is 7-4 with a 4.08 ERA in 14 starts and 86 innings this season. Arizona currently has the second worst record in MLB (37-53) heading into Monday night's game at home against the Marlins.