When Keith was drafted, he wasn't thought of as an elite skater, or elite anything, as evidenced by his 54th oa draft position. Adam Fox was picked 66th oa. Brock Faber, who has had a terrific first year, was picked 45th oa. None of these guys were thought to be anything special in their draft years. Going strictly by draft position alone, you could say that we aren't projecting him highly enough(please don't ask about Bogosian, G Reinhart, or Cam Barker).
The thing with all picks is how they develop. I think, if Buium gets stronger(likely), a bit faster(likely), and turns out to be a mentally tough, smart, adaptable player who learns to dig in on defense while still being excellent offensively then he will be really good top pairing player.
If he is a bit lazy, or entitled, and thinks he doesn't have to work and improve, then he will obviously be in trouble.