The Pirates placed Keller on the 60-day injured list Monday due to a right arm teres major muscle injury.
Keller's move to the IL comes just one day after he was lit up for seven earned runs on six hits and four walks in just two innings during Sunday's 10-2 loss to the Reds. The Pirates haven't provided an official recovery timeline for Keller, but his move to the 60-day IL makes him ineligible to be activated until Oct. 2, and the regular season concludes Sept. 27. The Pirates recalled Brandon Eisert from Triple-A Indianapolis to join the roster as a replacement for Keller, who ends his eighth MLB season with a 6-8 record, 5.29 ERA, 1.37 WHIP and 89:42 K:BB over 115.2 innings.