So suppose you have your basic Major League Baseball (MLB) structure, consisting of two leagues having three divisions of five teams each, each of which plays a 162 game, strongly unbalanced*, schedule. There are, of course, inherent quality differences in those teams; some are better than others, when assessed over some very large number of games, i.e. “asymptotically” **. The question thus arises in your mind as you ponder why the batter feels the need to step out of the batter’s box after each pitch ***: “how often will the truly best team(s) win their league championships and thus play each other in the World Series”. The current playoff structure involves having the two wild card teams play each other in a one game elimination, which gives four remaining playoff teams in each league. Two pairings are made and whoever wins three games advances to the league championship series, which in turn requires winning four games.
I simulated 1000 seasons of 162 games with leagues having this structure. Inherent team quality was set by a normal distribution with a mean of 81 wins and a standard deviation of ~7, such that the very best teams would occasionally win about 2/3 (108) of their games, and the worst would lose about that same fraction. Win percentages like those are pretty realistic, and the best record in each league frequently falls between 95 and 100 wins.
1) The truly best team in each league makes the playoffs about 80 percent of the time under the current system, less when only four teams make it.
2) That team wins its league championship roughly 20 to 30 percent of the time, getting knocked out in the playoffs over half the time. It wins the whole shebang about 10 to 15 percent of the time.
3) Whenever MLB expands to 32 teams, in which the playoff structure will very likely consist of the four division winners in each league and no wild card teams, the truly best (and second and third best) teams in each league will both make the playoffs, and advance to the World Series, less frequently than they do now.
This type of analysis is generalizable to other types of competitions under structured systems, at least for those in which the losers of individual contests live to fight another day, or if they don’t, are replaced by others of the same basic quality. The inherent spread in team quality makes a very big difference in the results obtained however. It’ll apply very well to baseball and hockey, but not so well to the NBA, for example.
So the next time an MLB team wins it’s league, or the World Series, and you’re tempted to think this means they must be the best team in the league (or MLB overall), think about that again. Same for the NHL.
* Currently, each team plays around 3 times as many games against each intra-division opponent as inter-division opponents, not even including the 20 inter-league games (which I’ve ignored in these analyses, assuming all games are within-league).
** These records are conceived of as being amassed against some hypothetical, perfectly average team. This team is from Lake Wobegon Minnesota.
*** It is perfectly OK to think other things of course, and we need not worry about the particulars of the language embodied therein.