The offense in year one was bad and they felt if he couldn't win the job then maybe he can't perform in this offense.
Secondly, and secondarily he played poorly in the bowl game in that offense so people feel Their fears were realized.
I can accept their worry but disagree. Last year was unique in a lot of ways. Tanner is set for a big year. His head coach has said as much. He has the talent and ability. And I think we see receivers who performed badly last year excel with tanner, just as the evolution went from 2014 to 2015 with guys like Blackmon.