With three weeks to go in the season, over half of baseball is still in the race. Seventeen teams are within five games of a playoff spot. You might think that's mostly due to the new second wild card, and that's the case in the NL. With all three division leaders comfortable and the Braves safe at the first wild card, the only hope the Cardinals, Dodgers, Pirates, Brewers, Phillies, and D-Backs have is Bud's new baby. I bet only half of that group will have a shot by this time next week.
But the AL is in a state of extreme entropy, or, if you want to get technical, clusterfucktion. Three games separate the top three in the East (including a tie at the top), one separates the top two in the Central, and three separate the top two in the West. Of the eight teams with a 38% chance or greater of making the playoffs according to BP's playoff odds, only the Rangers are a shoo-in. Mathematically, there are
35 29 different ways to fit seven teams into the last four spots, regardless of the order. There are still thousands of ways the AL could be seeded.
Under the new system, it's very likely that there will be some intrigue in September even if the top few teams have separated themselves from the pack, as in the NL. However, what's happening in the AL would be interesting under any set of playoff rules in baseball's history. No above-average team is much better or worse than any other above-average team.
The question is whether this is unusual. Are baseball fans witnessing a historically close league, or has this happened before? To get an idea, I compiled the top seven winning percentages in each league since baseball split into six divisions (1995). Since I was concerned with the race and not the final result, I took the standings as they were in each year on the morning of September 12th. Then I found the standard deviation for each group of seven. The result is a measure of how far each team was from the average. It would have been simpler to take the difference between the best team's record and the seventh-best team's record, but that would ignore the other five teams. Here are the results, sorted in order from lowest to highest (or closest to furthest away):
The short answer: it's not unusual for baseball as a whole, but it is for the American League: 2012 is the tightest AL year by a wide margin. The top three winning percentages are all below average and the fifth- through seventh-best records are all above average (the fourth-best record is dead on). There are a lot of possible explanations: The Yankees and Red Sox have the worst combined record of any of the years studied, the extra playoff spot encouraged teams to stay in the race, there's a renewed sense of community and everyone just wants to be closer to each other, etc. The most likely explanation, though, is random variation. The top half of the league just happens to be really even this year.
Count me among those cynical about MLB's new playoff format — I think it dilutes both the regular season and the playoffs. But if there were ever a time where it made sense, it's this year's AL race. The Rangers are only the best team by default, and it's impossible to separate any of the next seven from each other. The extra spot adds an order of magnitude to the complexity of the situation without taking away any well-earned playoff advantage. There's a good chance that the last 20 games of the season will be as exciting as any in history.