Reyes has been called up by the Cardinals after the team placed Michael Wacha (shoulder inflammation) on the 15-day DL on Tuesday.
Don't be misled by Reyes' 4.96 ERA and 1.46 WHIP this season in 14 starts with Triple-A Memphis, he offers a big arm with the potential of being impactful with his ability to pile up strikeouts upon arrival (he had 93 in 65.1 innings at Memphis). The Cardinals have not officially clarified his role, but it's reasonable to think that Reyes will simply replace Wacha in the rotation unless they suggest otherwise.