Frankly, with the timing and who he was, with this offense, it's more likely to be an addition by subtraction than a big loss.
Plus, you're talking like it's still August 2016. We've already had spring ball and its a lot more than coach speak when they can't shut up about how far Mangum has come. Time to learn the offense, and no weird conflict with another QB. He's THE leader. No more dealing with being the man, then someone comes back, but he's not all the way back, so you're kinda the leader in the offseason until he's fully healthy, but you're really not,then not anymore, etc. This is his team and Detmer loves where he's at.