Saturday, April 7, 2012
Was Intentionally Walking Sean Rodriguez to Pitch to Carlos Pena in the First Inning Defensible?
After sleeping off my annoyance about how the season opener went, I thought I’d look at the statistical implications of Joe Girardi’s tactical decision to walk Sean Rodriguez to get to Carlos Pena with runners on second and third with two outs in the bottom of the first inning yesterday.
The first thing I’ll say is that previous batter/pitcher matchup statistics are generally not predictive, as shown in The Book. So to me, the most relevant statistics are these CAIRO wOBA projections.
Rodriguez: .305 overall wOBA, .322 vs. LHP and .295 vs. RHP
Pena: .340 overall wOBA, .308 vs. LHP and .353 vs. RHP
The next thing I’d look at is run expectancy.
Using the run expectancy numbers from 1993-2010 we see that a team with two outs and runners on 2nd/3rd is expected to score 0.280 runs. With two outs and the bases loaded, they’re expected to score 0.334 runs.
So is it better to face a .322 wOBA hitter (Rodriguez vs. a lefty) with a run expectancy of .280 or a .308 wOBA hitter (Pena vs. LHP) with a run expectancy of 0.334?
Actually, forget wOBA. Let’s use linear weights instead.
Here are the linear weights values for the primary offensive events with runners on second/third and the bases loaded.
I don’t know why the RE for the HR isn’t equal to base runners plus batter, although I’m guessing Jorge Posada’s base ruining is involved in some way.
And here are the percentages of times Rodriguez and Pena would project to do each of those things vs. LHP.
|split vs. lhp||1b||2b||3b||hr||bb||out|
Multiplying those percentages times the run expectancy for that situation gives us this.
|split vs. lhp||1b x RE||2b x RE||3b x RE||hr x RE||bb x RE||out x RE||RE|
Add it all up and you see that the RE for pitching to Rodriguez with runners on second and third is lower than the RE for pitching to Pena with the bases loaded.
These REs for the values of a single, double and triple don’t factor in the outs, which means that we should probably expect a higher percentage of runners to score from second and third with two outs since they’ll be running on contact. That probably closes the gap some. But this shows me that it was likely not the right move to walk Rodriguez to get to Pena.
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