If the top 5 teams split the games fairly evenly then you're left with 5 teams that are basically interchangeable. The NCAA isn't going to take 5 teams from Conference USA no matter what. Or even worse you have one or two teams that have very good records going into those last 4 games and then lose 3-4 of them and you go from having two strong resumes to zero. And it still doesn't prevent the top seed from flaming out in the conference tournament. Very few mid-major/non-P5 conference teams are going to be able to survive that regardless of what they did in the previous 4 games.