All of the teams remaining either:
1) Won their conference regular season title (all except Oregon).
2) Won their conference tournament (all except UCLA).
3) Won the regular season and conference title (all except UCLA and Oregon).
Anyone that says conference tournaments aren't important should be beaten with a stick repeately (g). Seriously, I think the conference tournaments gets a team ready for the NCAA tournament. Last year UCLA and Florida won their conference tourneys and ended up in the finals.
I can't remember a year where all the 1s, three 2s, and a 3 are in the elite 8. It's been a highly competitive tournament with most the games undecided until the end.