I remember James Hurst making him quit and later Spurrior saying Clowney told him afterwards he was sick. Watching his effort in that one game alone made many question his desire, heck I remember the announcers called him a quitter in that game.
You may recall that NCSU beat Maryland in 73-74 tourney championship game 103-100 (OT) in what's known as one of the greatest games ever. NCSU was ranked #1 and went on to win the national championship and although MD was ranked #3, they didn't even into the national tourney.
I can see you're really young, because back in those days only conference champs made the tourney.
Expansion of field
The NCAA tournament has expanded a number of times throughout its history. This is a breakdown of the history of the tournament formats:
1939–1950: 8 teams
1951–1952: 16 teams
1953–1974: varied between 22 and 25 teams
1975–1978: 32 teams
1979: 40 teams
1980–1982: 48 teams
1983: 52 teams (four play-in games before the tournament)
1984: 53 teams (five play-in games before the tournament)
1985–2000: 64 teams
2001–2010: 65 teams (one play-in game to determine whether the 64th or 65th team plays in the first round)
2011–present: 68 teams (four play-in games in the first round before all remaining teams compete in the second round)