The first thing to notice is that the regular season is much better at finding the best team across every sport. If that was our only objective, we’d be better off following the European Football’s lead and having no playoffs at all.
The second thing that jumps out is the slopes—the lines for NBA, NHL, NFL, and NCAA Basketball look almost parallel, while college football and MLB are outliers for different reasons. College football’s best team wins the title more often than the NFL’s despite having the best regular season record at the same rate. The MLB’s best team, on the other hand, wins the title less often than expected given their regular season performance. This is due to the length of their regular season—162 games—almost twice as many as any other sport—meaning the actual best team more frequently is the best regular season team.
Looking at the title winning chances for the best teams, college basketball is the most chaotic, while the NBA is the best at unearthing the truly best team. This is unsurprising when comparing the postseason formats for all sports: the NBA, NHL, and MLB are the only ones to use series in every round of the postseason, usually 7-game series. This tends to balance out the randomness, giving the better teams the opportunity to recover from an off day. In practice, this makes the NHL and MLB basically identical to the NFL, where each game has less randomness, but where the playoffs are single elimination. The NBA has less randomness on the game level AND 7-game series throughout the playoffs, leading to a more accurate and less chaotic result.