Some players just look a certain way on the football field. They stand out for any variety of reasons. That's Allen.
I watched a slo-mo replay of one catch he made when he had to contort and extend his body to catch the ball, and it looked like he had hands the size of Shaq. His hands simply engulfed the ball. And I love the way he is a true hands-catcher. That means he has a larger catch radius and allows for more RAC.

He's a long strider, so while he doesn't look fast, he eats up ground very quickly.
Another year in the weight room will help his blocking.

At the least, we have a competent young TE2. We might have a very good TE1. I'll bet McVay gives this young man a lot more playing time the rest of the way to find out more about him.