IIRC Rottier struggled with the speed of Defensive Ends during his few games at tackle. That doesn't mean he can't improve and become a good tackle. Should be interesting to see whether he adapts or has to switch back to guard.
It is a similar situation to the Bauman signing. It is based on projection not merit.
Obilovich is doing the same thing in the Mallet and Burris signings. All Based on projection.
The more moves like this you pull the more the law of average works against you.
It is going to be a fascinating season. Some teams are going to win/lose BIG.