There are seasons that are truly dominant, yet cannot really be quantified by normal statistical means. For example, there was Fred Dunlap‘s 1884 season for the St. Louis Maroons of the Union Association. He produced a .412/.448/.621 batting line, which led to an OPS+ of 256. That would be the record until Barry Bonds 2001 season, when he posted an OPS+ of 259.
While baseball had not seen a season like the one Dunlap produced for 117 years, the KC Royals Wade Davis is in the midst of a historic run as well.