I think the key now is not to overreact. Braves have a great offense and a great bullpen. They've got a decent set of back-of-the-rotation options in Gwinnett. They can patch things together and don't have to make a move unless the wheels fall off.
Smith-Shawver should spend as much time as possible in Gwinnett. He was rushed last year (which has unfortunately become a pattern throughout baseball) and needs to sharpen his secondary pitches. I was just listening to Pedro Martinez on The MLB Network and his assessment as that too many young pitchers are rushed up through systems and haven't built up enough strength and endurance and further that teams don't work as hard building sound mechanics.