have a playoff large enough to include all the teams that could possibly be the best in that sport. College basketball does this well; we argue every year that so-and-so should be in or out, but no one ever argues that if they were in, they'd have a legitimate shot to win the whole thing. No doubt whatever, the best team in the sport is in the playoffs.
This is also true for the NFL, NBA, NHL, and every other sport, professional and collegiate, with one exception: college football. Even now. A four-team playoff, structure it how you will, willl routinely leave out one or two teams that, for whatever reason, were not judged good enough to be included, but that could legitimately make the argument that they're good enough to win the whole thing.
Four teams is not enough.