I seem to be observing that when AA prices F fairly low - it is on flights that normally had provided some upgrades.

I think AA has done the analysis of past flights and determine the number of people upgraded on a given flight. And on those flights they release more "I" fares (discount First/Business). And in some cases I am taking the bite and buying it. I have even had a situation where it was cheaper to return in First rather than a cheap coach return.

As an EXP, my upgrade rate has dropped to zero, the past several months.

I returned on a flight yesterday in paid F from SNA. In this case, on both segments through ORD, all passengers on the upgrade list cleared - so I probably would have cleared if I had not paid for F. Although - being Father's day might have had something to do with it. No upgrade though on coach flights out a couple of days before.

At least out of DCA - I have seen as many as 20 EXP;s on a flight and I have been #15 .