I want to say I remember Tunsil struggled on the right side is rookie year in camp, but I'm not 100% sure of that.Perhaps they feel Williams could make the transition with less difficulty? I would have no problem with them pursuing this if the goal was to keep them both long-term.
The problem is, Williams probably wants in the $15 million range and Tunsil more than that. $30 million plus on two guys and you still have the least talented interior line in the NFL. Plus you are giving up day 2 compensation for Williams.
Its one thing if this was a playoff team and Tunsil went down with an injury, but injury prone and over thirty just to place him at a lesser position but pay him like he was the primary guy would be a terrible move.
Miami has no reason to do this move in the state the team is currently in. Inquiring is just due dilligence at this point.