The college game is not perfect. It is not a perfect translation to the NBA for sure.
Teams tend to play slower. Zone defenses tend to clutter the paint. The shortened three-point tends to condense space. The big man is often still viewed as a traditional back-to-the-basket player. Teams have not quite embraced the spread-it-out, stretch-4 styles of the modern game.
And that does not even get into the pressures of managing upperclassmen who can help a team win with the young freshman who always seem to have one foot out of the door.
There is a long list of players who seemed to be cramped and compressed in the college style of game that do not get the chance to spread their wings.