Mills (elbow) signed a two-year minor-league contract with the Red Sox on Sunday, Chris Cotillo of The Springfield Republican reports.

Mills (elbow) underwent Tommy John surgery Wednesday, Mac Cerullo of the Boston Herald reports.

Mills' scheduled live batting practice session on June 9 was canceled due to continued soreness in his right elbow, MLB.com reports.

Mills (elbow) won't throw in an extended spring training game this weekend, Christopher Smith of The Springfield Republican reports.

Mills (elbow) was transferred to the 60-day injured list Sunday.

Mills (elbow) has resumed throwing and playing catch from 60-65 feet away, Chris Cotillo of The Springfield Republican reports.

Mills (elbow) began playing catch this week, Chris Cotillo of The Springfield Republican reports.

Mills (elbow) was placed on the 15-day injured list Thursday, retroactive to March 27.

Mills will begin the season on the injured list after being diagnosed with a flexor issue in his right arm, Chris Cotillo of The Springfield Republican reports.

Mills will be shut down for several days after experiencing elbow inflammation coming out of his most recent Grapefruit League appearance March 13, Chad Jennings of The Athletic reports.