Per Christina Chambers of WBRC:

Tyler has played just a handful of snaps during the first game of the season against Alabama A&M. It’s unclear if he has sustained another injury to his shoulder or if this is a lingering problem related to his shoulder surgery in the summer of 2016.

Tyler is brother to UAB’s standout linebacker Thomas Johnston. If he is granted the redshirt he’d have four years of eligibility left starting in 2018.