Remember this guy in the adjacent photo?
The center position in college basketball has changed.
Many players that theoretically have the size to play on the block are now outside shooters, a product of how the game has changed at almost every level. So much so, that a lot of teams play without a true post player.
There are a number of good post players, or centers if you will, in college hoops. It's tough to eliminate all outside shooters from being included in a list of top centers, but part of the criteria for the players on this list is that they have to do most of their offensive and defensive damage in and around the paint.
Some of these players can, and do, step outside the paint from time to time, but because of their prowess down low they were included on this list.
Incoming freshmen were not included in this list.