The returning players have a leg up on knowing the playbook, and the coaches will put the players that execute plays properly ahead of those who don't during camp, as an example. Talent will win out when determining who will play in an actual game.
Also, one thing to consider is that, with the exception of CJ James on the D Line, none of the transfers were consistent starters on their previous teams. They're either MAC level players that preferred to ride the bench at a big school early in their careers but now want a shot at playing time, or they're injury riddled and won't be able to provide major minutes all season. Still, the depth that these players provide is invaluable to a team that wore down quickly last season.