Good point.
You'll still find though that over time any affiliate with a good volume of traffic will end up with enough winning players that it averages out.
A good example would be a Bodog account I have where the monthly deposits between all players are usually $1500-$2000 but the rake every month is constantly over $5K. This is because there are quite a few small players I've had for years that slowly build up a bankroll and cash out a bit at a time. This is just one account I recall because I've always found it interesting how sometimes my commission at just a % of rake is higher than all my players combined deposited in a month, and we don't offer rakeback there.
Anyways point being that it all averages out in time. Of course when first starting at a room the fees will be higher, but this is of course small sample size. I doubt in the long run anyone with even medium sized volume ends up earning less than 20% at cake, perhaps I'm wrong.
I guess maybe for smaller affiliates that PAW deal would be better than I though. Initially i though that the CPA w/ MGR was a bad idea because my experience has been that cake player value is out rageously high compared to other sites.
Anyways sorry to hear about your 3%
I have a similar situation with Carbon Poker. its not fees it just that each month i earn less than $1 per player I sign up and I have many hundreds signed up total