The re-rated rosters that you see in this forum are not being re-rated to make more accurate Madden draft classes. They are being re-rated because 98-99% of the default attributes are incorrect.
It is impossible to get any kind of draft classes that are even 1% accurate, if you try to export your own draft classes from any of the files in this forum. Feel free to try it for yourself so that you can see for yourself. The reason is not because the NCAA rosters are that inaccurate, it is because when you export a draft class, the overall ratings of the players and their individual attributes are created randomly.
If you're looking for Madden draft classes, you should go to the Madden section of this board. A few people are trying to create better draft classes than what you will get from just exporting classes from a "normal" NCAA roster file.