Jim Thomas and Bill Coats of the St. Louis Post-Dispatch both believe rookie WR Greg Salas' roster spot is safe, though Austin Pettis may not be so fortunate.
Salas has flashed in camp practices and preseason games, and "shown a knack for getting open on underneath routes, at times looking almost like a bigger Danny Amendola." He also possesses better RAC ability than Amendola, which may give us a hint about the latter's long-term outlook in St. Louis. Pettis has practiced well only to disappear in exhibition games.
I am going to say the same thing I said about Golden Tate. You don't spent your picks in your first 4 rounds, to dump them before you give them time to prove themselves. Salas and Pettis have only been on the field with the teams for a handful of weeks in a shortened preseason. These guys will make the roster this year.