I don't know that it has ruined the college game, but it certainly does not enhance the college game. It has enhanced Kentucky and Duke, otoh. But the reason for the NBA's rule in the 1st place was not to help the NCAA. It was to help the NBA. You had the occasional LeBron back in the day, but more often you had guys with great potential washing out of the league too quickly. The NBA wanted the rule to get a look at a prospect with 1 more year of development at a college away from the kid's home. It's like a year at a hoops finishing school like Oak Hill but on steroids. In that year, the prospect has worked a lot with a college strength coach, hopefully a good college coach and has gotten used to the travel and grind to better prepare that prospect overall for what the NBA is going to be like. The NBA will be changing its current rule, but that's going to make it even more of a crap shoot for NBA GMs.