Paul Kuharsky makes a really good point in his Titans Camp Confidential about the use of the tight ends in the offense this season:

I’m not sure how the Titans will distribute their tight ends without tipping their intentions. [Jared] Cook is the receiver and Craig Stevens is the blocker. Veteran addition Daniel Graham can do both but is more a blocker.

We are all really excited about what Cook can bring to the offense, but he will only be truly effective if he can block enough to stay on the field for some running plays. If they only run him out there when they are going to pass it isn't going to be very effective.

The old coaching staff wanted Cook to be able to completely play all phases of the position before putting him on the field.  The new staff won't go quite that far, but they will still need him to at least hold up on run plays to get the most out of his potential.