Trying to watch what footage I can find from camp. From what I can tell, he does a good job coming out of his cuts on routes that break to his left. There are several examples of that from camp and even one of his catches against Seattle. He broke left on a crossing route and got good separation. I do think his speed (or lack thereof) shows up on some of his deep routes/end zone routes, but he's such a good contested-ball receiver that he's making plays anyway.
That's just an incomplete observation on my part based on what we have to go on. In college, it didn't look like he got a lot of separation, but just made the play anyway, but I have seen some decent separation by him on throws to the flat or comebacks the break to his left. His ability to make those deep, contested catches makes those routes more effective because DBs have to respect him deep even if he can't outrun them.