Folks the Big 12 could lose every first round game and it is what it is. A single elimination tournament doesn't compare to an entire season.
But in the end, the country is full of players that can play really good basketball. It has coaches that can coach at a really high level. This isn't like football where pure athleticism, size and talent make upsets just harder.
So yes, the Big 12 is the best conference, but this is basketball where one team could have an off night shooting or an on night shooting. The sport is much more volatile than a sport like football.