Ayala's 96 season was spent in a hitter's park -a good hitter's park. That may make his stats league avg. after you include the park adjustment.
Chili: I've read alot of the stuff on Baseball Primer and Fanhome and I still am not sure that the folks that advocate for negative values are correct in their thinking. True replacement values (as D-Man alluded to) seem to move all over the place.
Also, in the case of Ayala -how do you know when to send him down to bring up a replacement level player? Seems as if you can only do that once you know where replacement levels have been set...after the fact. It would be silly to send him down to bring up another player who would be replacement level quality until you know what those values are. Ayala had, at that point, 2 good seasons in a row- how do you know when to throw in the towel and bring up the replacement level player? Based on what values? Good god, I sound anti-sabermetrics today, but i think I'm making some sense.