First, NBA failure doesn't mean someone is a poor college coach. The skills for success at each level overlap, but there are key differences. Few college coaches have made the transition successfully. Brad Stevens has done well so far, and Pitino was doing pretty well with the Knicks before he left to take the Kentucky job; but Pitino was terrible in Boston, and he isn't the only successful college coach who failed in the NBA. Mike Montgomery, Lon Kruger, Leonard Hamilton, Tim Floyd, and Jerry Tarkanian are examples.
On to Calipari at Kentucky...
His teams are pretty hopeless in November and December, uber-talented young guys who have no idea of how to play together. By March, Kentucky runs a credible halfcourt offense and plays decent team defense. It's nothing fancy; but with that kind of talent, it's enough to send Kentucky into the tournament with better odds to win it than almost any other team.
I have no idea how Calipari would do with talent comparable to "normal" programs. He might not be particularly good with four year players who have to develop year by year; but that isn't what he does. He has chosen a different model for his program; and with his school supporting that choice, he has been very successful.