One thing I think it might do well to point out: OOTP is relying on the Lahmman database as an inexpensive way to have all of baseball history at your fingertips. I think it's always going to be extremely difficult, and probably impossible, for any game engine to take the data contained in the Lahmann and come up with the kind of accurate statistical replay that would interest someone like Styx. I don't know what Action does, but I know that the people who do season disks for DMB do thousands of runs through a given season, tweaking things like fielding ratings to get the best possible stats reproduction. There is always room for variance within the results, but the emphasis there is on the type of accuracy Styx talks about. Hard for any game using Lahmann to compete with a hand-tooled single-season disk done by people who know their stuff.
For what it's worth, I only play fictional with OOTP. DMB is still my game of choice when I want to "watch" the real guys in action. Action does look like an interesting game for historical too, but I'm not sure I want to go in another direction after all this time, with to cost of all the season disks to think about. It's kind of like chucking your PC and going Mac!
I think OOTP excels in a fictional setting, where you don't have expectations of a player's performance based on his name.