I like him. It's a mistake to think that just because he didn't put it all together in college, he never will. Pro coaching will be good for him. As stated above, he has the size, the speed, the vision, the shot to be an NHL player. He's 22, so he has ~3 more years of development to go, one of which is regarded as prime development year (development usually slows down after 23-24, stops after 25-26).
It's not true that Boo's potential is as a 4th liner. He could easily be a quality top-9 guy.
Gotta admit - I don't see it. He just doesn't have the hands - which isn't terribly uncommon for guys with higher-end speed.
I think there's a misconception that he didn't "put it all together" in college. I think he did very well with the tools he has, I just think those tools don't include a higher scoring ability.
Speedy guys always seem to have an unfair bias against them. For starters, it's almost always assumed that speed = scoring and that's not always a fair expectation.
Adding to the challenge, when they don't put up lofty offensive numbers, there's always a perception that they're underperforming or a disappointment.
If Nieves makes it, and I wouldn't incude him in the top two tiers at this point, I can't help but think it'll be because his speed is utilized as a disrupting force --- not necessarily as a guy who generates a lot of offense.
Having said that, he could be one of those guys who really comes alive as a pro when playing with a better cast of teammates. But generally speaking, a guy whose hands aren't a strength at the lower levels usually doesn't become a scorer at the pro level.