Marvin Haglar was 5'9" and Alexis Arguello was 5'10". I think that is a good example of how fighting weight depends more on bone structure, and natural physique than hieght.
I am 5'10 and walk around at 175-180 with good definition. I'd have to kill myself to make SMW let alone MW. I think it depends on your body type. I am an Endo-Mesomorph which means I gain weight and muscle relatively easy. i believe Abraham is only 5'9 and he is a looks like a friggin monster.