Worth remembering that Abraham is pretty short for a MW at 5'9". He might not even be that. He can't possibly decision Williams. He has to knock him out and that's going to be tough against a guy with great height and reach, a high volume punch output and good stamina, aswell as a decent chin (although Abraham CAN knock him out if he finds the right punch, definately).
Reach don't matter for AA - if you aren't a defensive genius (and PW is not even good defensively), he'll take his time, feint you for an opening and when you think you're trough it's lights out baby...
This guy loses 6 inches to PW. He also loses workrate, and PW is southpaw. PW also has as good a chin as anyone, as he has never ever been knocked down. AA would and should be favored, but he would have his work cut out for him.
Margarito is 6' and Williams is 6'3". HBO make their stats up. I'm making mine up as well, but they're more accurate.