Pierce dropped because he was considered a "tweener" and a scorer without great athleticism. Pierce didn't have especially good handles, was not considered a great passer and was thought to be too small to finish inside. He was considered a post-up shooter.
While some of that is true, Pierce also was plagued with the tag of mentality soft as when the biggest game of the year came up, he disappeared, namely his horrendous showing in the NCAA tournament that year.
With LaFrentz and Pierce, the Jayhawks were favorites to breeze through the regionals and straight through the Final Four to a title. But Pierce was a no show for that second round game against Lamar Odom and Rhode Island and it cost his reputation big time.
That's why Pierce was so driven to prove the teams who passed him over were wrong. They questioned his heart more than they questioned his skill and it ate at him terribly.
When Pierce wasn't chosen second in that draft the announcers were shocked. When he wasn't chosen third they were more shocked. And so on it went with the announcers constantly questioning why he wasn't being selected and always referencing that KU/URI game.
Until I see a link telling me otherwise, that is what I remember about the whole incident. And I remember it like it was yesterday because after the Duncan draft lottery fiasco, I thought Pierce dropping into our laps at 10th was the beginning of a turnaround in Celtic luck and history. How little did I realize that I was right but that that luck wouldn't pay ultimate dividends for 10 years. But at least Pierce got to have the last laugh over Odom.