Here's a portion of what Polian wrote:
The most likely competition for Tannehill is the Cleveland Browns at No. 4 overall. That means, in order to assure themselves of selecting Tannehill, the Dolphins would need to move up to the No. 3 pick in a trade with the Vikings. In my mind, this is a trade you must make if you're the Dolphins. There is no reason to gamble and hope that he falls to No. 8. With the new CBA, Tannehill's position as a QB and his contract wouldn't be an impediment to moving up to No. 3 to select him. And even if the Browns do pass on Tannehill at No. 4, there's no guarantee a team like Kansas City won't trade up to take him.
With the Dolphins owning a plethora of reasons to trade up, does their potential trade partner -- the Vikings -- have an incentive to make a deal? In short, yes they do. Minnesota has a clear-cut need at left tackle and at the top of the draft, there are two such prospects that could fill that void: Matt Kalil of USC and Riley Reiff of Iowa. Given the current draft order, it's likely that the Vikings will be able to get at least one of them with the Dolphins' No. 8 pick.
However, it may not be Kalil, the prospect many grade as the draft's top tackle. If the Vikings believe the trade package from the Dolphins to be worth the drop off in grade from Kalil to Reiff, I think they'd move the pick.