Wednesday, December 18, 2013

A quick note on lead-off hitters

The prevailing wisdom for a long time was that lead-off hitters needed to be fast and steal lots of bases.

The modern wisdom is that lead-off hitters need to get on base.

I was involved in a discussion regarding this and broke out the Excel sheet so I figured that I'd do a quick post.

I took a look at how often runners score compared to their ability to steal bases and their ability to get on base.  I looked at all hitters from 2013 who had more than 200 PA's.  I looked at runs scored/PA.  I looked at SB/PA.  And I looked at OBP.

Here's what I found.

You can see that in the top graph of Runs & OBP.  As OBP (the horizontal axis) gets bigger the number of runs per plate appearance also gets bigger.  

In the bottom graph as the number of stolen bases per plate appearances per plate appearances gets bigger so does the number of runs per plate appearances.  But the relationship is not nearly as well defined as in the top graph.

The number in each graph, the r-squared value, tells the strength of the relationship between the two variables.  A perfect correlation where in each instance as one variable goes up so does the other would have an r-squared of 1.  A correlation where the two variables had nothing to do with each other would have an r-squared of 0.

We can see that the r-squared for the bottom graph (stolen bases and runs scored) is .09.  That's very close to zero, meaning there's very little relationship between stolen bases and the number of runs scored.  In the top graph, the r-squared is .34.  That's a much stronger relationship between OBP and number of runs scored.  

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