Than just diameter.
It's good that recently lug to lug has been another reported metric for sizing. But another very important stat is the dial vs bezel size. For example, I have a x-33 that's 45mm (!) listed, but it wears better than a jlc MUT at 40 mm because of the dial to bezel ratio - a lot of the x-33's measurements are from the bezel and bumper, but all of the MUT is big dinner plate dial. I have a 6.75" wrist, so normally 45mm would be completely out for me.
When you really get down to it, bezel color makes a huge difference as well. I tried on the rhodium YM37 a while back, I really wanted to like it but it looked too small for me. But I expect the bb54 will be just right, because the matched bezel color will make the dial look bigger rather than fade into the bracelet.
