Why is it that all great college players suck in the NBA?

Now that we wee what has befallen Greg Oden, it begs the question: Why is it that all great college players suck in the NBA? That is not always true, but many scouts in the NBA and NFL are swayed by individual performances/statistics about players away from the field. For example, when the Philadelphia 76ers selected Shawn Bradley with the 2nd overall pick in the 1993 NBA draft, they did so because he was 7' 6''. At that time, he was the tallest player in NBA history. Certainly, he should be able to be a quality player because he is so tall. The scouts did not bother to look at Bradley's overall numbers in college at BYU. They focused on potential and flash and not performance and substance. Thus, as a result, quality college players like Penny Hardaway and Jamal Mashburn were selected afterwards. The same result occurred ten years later in 2003, when the Pistons selected Darko Milicic as the 2nd overall pick ahead of the likes of Carmelo Anthony and Dwyane Wa...