If you go by the numbers, the 2013 IndyCar championship was decided partly by Scott Dixon's phenomenal late-season charge, and partly by Helio Castroneves's Houston disaster.
It was a season in which the tea leaves rarely revealed what was coming. Ten different winners, Takuma Sato leading the points after Brazil yet ending up 17th, Castroneves battering everyone with a blend of pace and freakish consistency, only to have his gearbox crack in Houston.
IndyCar 2013. You couldn't make it up.