THE BOOK--Playing The Percentages In Baseball

Monday, May 05, 2008

How can the inputs remain the same, but the outputs change?

Joe Sheehan points out that the “slash” data is the same, but run scoring is down:

AL AVG OBP SLG ISO R/G
April 2008 .260 .334 .398 .138 9.04
April 2007 .255 .327 .404 .149 9.36

NL AVG OBP SLG ISO R/G
April 2008 .256 .331 .404 .148 9.11
April 2007 .258 .332 .400 .142 9.31

Is that random variation, or is something else going on?  Taking a quick crack at it:

We have in Mar/Apr 2007 in MLB: .256 .330 .402
And this year: .258 .332 .401

That’s remarkably close.  The runs scored per 27 outs in each year: 3785 runs in 7490.1 innings, 4.55 runs per 27 in 2008.  3360 in 6670.1, or 4.53 runs per 27 in 2007. 

Huh?  What’s Joe talking about?

Here’s the data I’m using:
http://www.baseball-reference.com/pi/psplit.cgi?team=TOT&lg=ML&year=2007#dates-month
http://www.baseball-reference.com/pi/psplit.cgi?team=TOT&lg=ML&year=2008#dates-month

Either Joe misstated his facts, or Sean has a bug, or I’m reading something wrong.

I’ll let the Wisdom of the Crowd make the decision.