Harrington debuted for Triple-A Indianapolis on Sunday after being promoted from Double-A Altoona earlier in the day and struck out four over 5.2 innings while taking a no-decision in Indianapolis' 10-8 loss to Toledo. He gave up five earned runs on six hits and one walk.

Harrington has thrown five-plus innings in eight straight starts for Double-A Altoona, logging a 2.80 ERA, 1.13 WHIP and 47 strikeouts in 45 innings over that span.

Double-A Altoona reinstated Harrington (shoulder) from its 7-day injured list Sunday.

Harrington (shoulder) has been sent to Single-A Bradenton to begin a rehab assignment, Andrew Destin of the Pittsburgh Post-Gazette reports.

Harrington has been diagnosed with a right rotator cuff strain, Jason Mackey of the Pittsburgh Post-Gazette reports.

Pirates director of sports medicine Todd Tomczyk said Wednesday that Harrington will be examined for a right shoulder injury, Jason Mackey of the Pittsburgh Post-Gazette reports.