The TE is a functional piece of the protections, they go hand in hand. You can't contribute as a pass catcher from a 3-point stance without first becoming an integral part of the protections. Guys that don't understand leverage because they've never done it require a steeper learning curve.
You try to make a kid as complete of a player as you can make him and it starts in training camp. They already know he can line up as a receiver, run option routes and catch bubble screens in his sleep. He's got 2 full seasons worth of game film doing it at Missouri... that's why they drafted him.
They'll flex him out, but you have to develope him as a blocker to become part of your protections or he's no good to you.