It's not obvious to any but its inventors, that the Avenger was created to compete with Baker's pancake; which was patented. All the makers quickly worked out how to honour his patent by realising the pancake style in another way.
A fully-realised avenger-style works exactly like a pancake, by keeping one outboard slot, and replacing the other with an outboard loop. Designers make a mistake when they simply 'put a loop on the back' as John Bianchi's does. That method works ideally for a true appendix carry (that is, at 2:00; anything further forward is belly carry) and for crossdraw; and both with the barrel strictly vertical (no caster at all, either positive or negative). Very different when doing a 'strong side' draw with a positive caster of, say, the 24 degrees that I use (which has been used since Myres in the '30s).
My current version (you'll also see it on that Aker from the Nineties in the main images) acknowledges the limitations of the avenger design (which is a tendency to turn the rear sight out) by placing the backside loop well out over the fold of the holster:
avengers study (3).jpg Nichols 'Beat the Devil' at left, John's (holster name keeps changing) on right
avengers study (4).jpg 'Nichols Avenger' for Aker in the '90s, the Galco 'Avenger' I did for them, prior to the Aker, at right
Both the Bianchi by Bianchi, and the Galco by Nichols, have virtually no camber so can have rear loops that are 'just anywhere'; as long as one wears them at 3:00 or 2:00. To be worn at 4:00 and have acceptable concealment and access, there must be positive caster; and then the basic loop won't permit them (concealment and access) to be acceptable.