Westbrook, 35, went 2-1 with a 1.62 ERA and 1.46 WHIP in 39 innings across six starts before being placed on the DL. He went 13-11 with a 3.97 ERA in 2012, which is right in line with what he's been doing for almost a decade now. Westbrook has been one of baseball's more reliable starters in recent years.
It seems likely that left-hander Tyler Lyon will be returned to Triple-A to clear a rotation spot since he was originally lined up to start Friday. The 25-year-old southpaw has gone 2-2 with a 3.51 ERA in four spot starts in recent weeks.
Despite losing Westbrook for a month and Jaime Garcia (shoulder) for the season, the Cardinals still have the best rotation ERA (2.73) in baseball this year.