He will always be a running quarterback, and as a result, susceptible to injury. He compensates for his weaknesses as a passer with his legs, resulting in catastrophic injuries nearly every year. And his Lisfranc injury last year definitely puts him in the "made of glass" category.
I love the guy, and desperately want him on the team for depth, but it just makes sense to start Tanner. I'm all for a fiar competition though. May the best man win.