He's never ran a full tree route. He also doesn't fight for the ball. He also doesn't have a very big catch radius. So the ball must be almost on top of him. You also play your hand with him in the backfield. He can't be allowed to block so he is always going to either run the ball (usually wide) or he is going out in the pattern.
Also find it interesting that nobody will talk about his fumbles or his inability to stay healthy. Do people really think the NFL is less rugged than the Mid-American Conference? Also he is not a punt returner. He did it 6 times for 8 yards. So he'll have a ton of stuff to work on. He has to learn to be a slot WR, learn to be a punt returner, and learn to not fumble the ball. That's a lot of learning for a 3rd round pick in one of the deeps drafts at WRs in years.