The Cardinals designated Shuster for assignment Saturday, Jeff Jones of the Belleville News-Democrat reports.
The 27-year-old will end up as the roster casualty necessary to make room for Matt Pushard's (knee) return from the injured list. Shuster has performed well during his time with St. Louis, allowing just two earned runs through 7.2 innings. However, his 7.25 ERA at Triple-A over the past two seasons could dissuade other teams from picking him up off waivers.