I know my play hasn't gone down. I also know my tier credits have seemed somewhat random. One time I got 57 tier credits and another time 14 for pretty similar sessions. (I also got 379 tier credits for one session, but I think they got me confused with the guy who was playing next to me and betting a lot more, as we both came and left.)

I realize that while airline programs are very transparent, casino programs are opaque.

I know my losses are way less than the average, as I play perfect basic strategy at blackjack (I'm actually positive over my last 4 trips, not that I expect that to continue) and only play the front line + odds at craps. But I know they don't figure that in, they just care how much you bet.