This is the only thing that is keeping Alex ahead of David on the offensive side of the conversation, so I thought I'd give it a little deeper look.
The difference between the two (.022) amounts to 2 extra times on base for every 100 PA or every ~22 games. This may lead one to ask where can you account for these extra non-outs? Ortiz has more HR (+1), 2B (+10), BB (+10), while Rodriquez has more 1B (+24), HBP (+14), and, strangley, they have the same amount of 3B. So, every 22 games, ARod will outproduce Ortiz by 2 singles.
How do those 2 singles benefit Alex's team? Statistically, they don't. Despite having more opportunities to score runs, Ortiz has scored one more run. And those 2 extra singles per 22 games have managed to score 13 fewer RISP (Ortiz 85 RBI RISP, ARod 72 RBI RISP) , with a lower probability of ocurring with a chance to score runners (Ortiz .345 BA RISP, ARod .291 BA RISP). Given the production that has resulted from that higher OBP, you will have to excuse me if I don't wet my pants with excitement.
All things considered, ARod's the MVP. But, I'll take Papi at the plate.