David was an All-Midlands selection at Killeen (Tex.) High School as a senior, where he was credited with five quarterback sacks during his final campaign. He began playing football as a safety, but grew out of that position after his prep sophomore year. McMillan also lettered in track at Killeen.

He redshirted as a freshman at Kansas and saw action in ten games as a reserve defensive end in 2001, recording 27 tackles (13 solos), two sacks and a forced fumble. He moved into the starting lineup at right defensive end in 2002, going on to start 37 consecutive games. McMillan posted a career-high 55 tackles (32 solos) with three sacks, nine stops for losses and twelve quarterback pressures as a sophomore.

In David’s junior campaign he made 31 tackles (20 solos) with three sacks, six stops for losses, four quarterback pressures, a fumble recovery and an interception in thirteen games. Primed for a banner senior campaign, he fared better than he did the previous season. While he only managed 37 tackles (18 solos) in 2004, he collected a career-high seven sacks and 13 stops behind the line of scrimmage to earn All-Big Twelve Conference honors from the league’s coaches.

McMillan started 37 of 46 games for the Jayhawks. He collected 150 tackles (83 solos) with fifteen sacks for minus 108 yards, 30 stops for losses of 146 yards and 19 quarter-back pressures. He caused five fumbles and recovered two others, intercepted a pair of passes and deflected three others. His 19 sacks rank seventh on the school’s all-time record list. Only Willie Pless (41, 1982-85), Jim Zidd (40, 1977-79), Algie Atkinson (35, 1998-2001), Mike Butler (33, 1973-76) and Nate Dwyer (31, 1998-2001) had more tackles behind the line of scrimmage in a career at Kansas than David’s 30.