Statistics and Girardi's Opening Day Intentional Walk Decision

Joe Girardi explained his decision to intentionally walk Sean Rodriguez and load the bases for Carlos Pena as follows:

   "Sean Rodriguez has hit (Sabathia) hard."

Of course if CC Sabathia executed his pitches, Pena would not have hit a grand-slam. However, that does not absolve Girardi from his responsibility for reading the current situation, which I saw as this:

• CC was struggling with his command.
• An intentional walk loads the bases, thus putting pressure on the pitcher to command his pitches.
• Carlos Pena has a good eye, as measured by his ability to draw walks, thus exacerbating said pressure.
• In that context, to me the only way an intentional walk is sane is if Sean Rodriguez were unarguably, significantly worse of a match up than Pena.

Girardi's justification was in the pitcher-hitter match ups, so let's look at some pertinent batter-vs.-Sabathia match up statistics:

Player	AB	H	D	T	HR	K	BA	SLG	BABIP	ISO
Rodriguez	21	6	2	0	1	5	.286	.524	.333	.238
Pena	35	4	1	0	2	19	.114	.314	.143	.200

The conventional batting average and slugging percentage stats suggest Rodriguez is significantly better against Sabathia than Pena. But that is superficial - the overall data also suggest this is merely an illusion, for these reasons:

• Pena's low BABIP suggests Pena may have just had rather poor luck against CC.
• The ISO stats suggest that both hitters have hit CC pretty much equally in terms of power.

Of course it's risky to read too much into the small sample sizes that typically constitute batter-vs.-pitcher match ups; but if you are going to look at such stats, stats such as BABIP and ISO give one some insight into how meaningful (or meaningless) they might be. 

Note: We don't know whether Girardi was looking at the above statistics, or some more sophisticated data. But we do know that whatever the stats were, they were of a small sample size. We also know that they could not have indicated CC owned Pena - if CC owned Pena he would not have given up 2 HRs in 35 ABs.

In this case, since Pena is a much more dangerous hitter than Rodriguez, and given the context of CC struggling with his command, etc., the intentional walk seems merely an abuse of whatever data Girardi was using to make this decision.