Look for Carpenter to bounce back after a rough outing his last time around. In his only start against the Reds this year back on 06/04 he threw a complete game allowing only 3 hits and 1 Earned Run. He has a 2.29 Career ERA vs the Reds with a 0.817 ERA.
In 3 of Arroyo's last 4 starts against the Cardinals he has given up 5 or more Earned Runs, with the most recent being on 06/02 where he only lasted 5.1 innings giving up 7 hits and 5 Earned Runs. The only good thing Cincy has going for them right now is that their bullpen is damn good. But I expect the Cardinals to continue to follow Pujols hot bat and jump on Arroyo early!