Bauer was originally slated to pitch against Pittsburgh on Saturday, but he hasn’t felt well for a few days. On Thursday, manager David Bell moved him back an additional day, but his health didn’t improve enough.
The Pirates will counter with right-hander Trevor Williams for the finale, which can be seen live on MLB.TV at 3:05 p.m. ET.
In 34 starts and a career-high 213 innings combined with the Reds and Indians, Bauer’s season ended with an 11-13 record and a 4.48 ERA. He was acquired in a July 31 three-team trade that sent right fielder Yasiel Puig to Cleveland.
Mahle will be pitching on short rest, but he lasted only 2 1/3 innings and 72 pitches during Wednesday’s 9-2 loss to the Brewers. He gave up eight runs (seven earned), including three home runs.
In his 24 starts this season, Mahle is 2-12 with a 5.34 ERA. For his career vs. Pittsburgh, he is 0-3 with a 4.61 ERA in five starts. The Reds went 0-5 in those games.