Baseball HR and SO over the years

From my upcoming Masters thesis, in baseball over the years, Home Runs (HR) and Strikeouts (SO) have been highly correlated (0.85).  Graphically we see this (values are scaled):

HR and SO by Year

HR and SO by Year

The Bill James Historical Baseball Abstract mentions a jump in HR’s in the 80’s and a jump in SO’s in the 90’s.  We see both of those here.  Perhaps most interesting is that for the 80’s HR spike, SO’s didn’t really keep pace that decade.  As James points out this was the first decade where players could finally make enough to play full time and work-out year round instead of selling cars in the off-season.  And of course there was probably drug use.

So you would think that if the wind were to have a significant impact on HR’s, you’d see its influence on the HR but not a corresponding influence on SO:

HR by Wind Direction

HR by Wind Direction

When the wind is blowing out at Fenway (Southwest wind) it does in fact appear as if there a slightly more HR’s.  Still the affect is hard to quantify.

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