Standard Deviation Through the Years

Just saw this nice set of graphs from fellow SABR member John Rickert that looks at the same question I addressed in my post Where have the .400 hitters gone?

Per John these are based on "3.1 plate appearances per game (the modern batting title qualifying level). On each page the first plot is the "regulars" average relative to the league average (regular - league) and the second plot is the standard deviation of the regulars' numbers."