I've written about that pretty extensively lately. If you look at the difference in MU's first 16 games (13-3) and final 10 games (3-7), the offensive differences were negligible. Scoring dipped a couple points and shooting percentage fell off a point or two. But MU's opponents shot the ball 7 percentage points better and MU's rebounding fell off dramatically. I think you can trace it back to a few developments:
* Tilmon's two-game absence and his offensive/defensive lull after he got back.
* Pinson was a defensive liability on the perimeter
* Pickett's ankle injury took him out of the rotation and forced Watson and Mark Smith to play more minutes on the wing.
And there's no way to prove this, but anecdotally, the experience and continuity advantages Mizzou had early in the year were no longer a major advantage by the end of the year when other teams had played more together over the course of the season.
All that being said, I would never make sweeping generalizations about one team based on the NCAA Tournament. It's way too small of a sample size. Illinois could still beat any team left on the bracket - but ran into a buzzsaw against Loyola. Oklahoma State and Texas were two of the hottest teams coming into the tournament and both were ousted quickly by double-digit seeds.