From Daniel Jeremiah at NFL.com:
Warren is a massive tight end who carried the Penn State offense this past season. He lined up in-line, in the slot and as a Wildcat quarterback. His production is the result of his size, catch radius and tenacity. He doesn’t generate a lot of separation as a route runner, but he walls off defenders when on the move. Defenders simply can’t get through his body to make plays on the ball. He can track the ball over his shoulder and he can high-point the ball when needed. He isn’t a nifty option-route type of player.