The Oline in 2013 was crap and we have to shore it up.
Not only because Tannehill getting sacked way too much, but to increase the effectiveness of our running game.
Yes, the RBs were pretty mediocore last season, but they didn't get much help from the line. They had rarely routes blocked free for them. Even Elite-RBs like Adrian Peterson wouldn't put up great numbers with this kind of support.
The WR-Corps isn't elite, but it's for sure above average. If Tannehills development is on-going, he could make them look better then they actually are. For this, he has to work on his reading D- and deep throwing-abilities. And of course, he needs more protection.