Rodriguez and Lidge - Comparing the Competition

I think I've mentioned before that I drive a POS truck with no radio and I drive about a half hour to and from work.  I usually use that hour each day to think of things to write about here (or lament about how crappy it is driving an hour without music).  During one of my trips I started thinking about the quality of hitters a relief pitcher faces and how it affects his stats.  There are many places to find a pitcher's stats showing what his batting average against is, but I couldn't find where it stated the quality of hitters a pitcher faced and how he did against them.  Obviously, if a pitcher faces the bottom half of a line-up he'll typically do better than having to pitch against the heart of the order.  Below are some number for Francisco Rodriguez and Brad Lidge.  They had similar numbers during the season, beside the Saves total, but I wanted to see if either pitcher benefited from facing weaker hitters.

First, here's their season stats:

There were approximately 284 plate appearances against Rodriguez and 288 against Lidge.  In those PA, the hitters each pitcher faced had these accumulated season totals:

To get these totals, I compiled a list of hitters each pitcher faced and then added the hitter's season stats.  Lidge faced marginally better opponents, which to me was surprising since I read about how much better the American League hitters are than National league hitters.  This might be a random event where Rodriguez happened to face weaker hitters over the season.  This is what their adjusted averages looked like.  Adjusted average is their AVG/OBP/SLG minus their opponents slash stats:

Looks like Lidge did slightly better than Rodriguez as the difference between the two pitchers' number increased due to Lidge having the better stats against better competition.   The next thing I wanted I looked at was how well each pitcher did against different levels of competition.

The cumulative season totals of the hitters each pitcher faced: