The 2016 Chicago Cubs were the most extraordinary team in baseball history. Not because they won 103 games in the regular season -- there have been 36 other teams that've done at least that well. And not because they won the World Series -- every season ends with someone winning the World Series. In these ways the Cubs were great, but they weren't exceptional.
Where the Cubs really shined was in preventing hits. If you don't give up hits, you don't give up runs, and the Cubs allowed opponents to hit just .212, the lowest mark since 1968. That's remarkable already, but more than you might think from just that number.
We have to turn to Batting Average on Balls In Play, or BABIP, a stat that suffers from long-acronym syndrome but is really quite intuitive. All it describes is batting average on at-bats without home runs and strikeouts. It functions as a good measure of team defense. The Cubs allowed a BABIP of just .255, putting them absurdly ahead of the rest of the majors last season:
Every so often, when a team does something unusual, there are fans who suggest they've "figured something out." Team X has figured out how to reliably win one-run games. Team Y has figured out how to hit particularly well in the clutch. Just about every time, it's hogwash. Teams don't have their own secrets that are close to that important. In the case of last year's Cubs, though, this is at least what it would look like if a team did have something figured out, some kind of informational advantage all to themselves.