I am sorry but this physical characteristic is as important as reach and height. For wrestlers with a good back and legs, small hips very easy to manipulate. It will feel like Bobby is a weightclass or two lower than Islam.
Edit: of course having wider hips alone can tell only so much, as with people with reach who are often seen failing to utilize it. Note that I said, "For wrestlers with a good back and legs", which doesn't mean they themselves need big strong hips.
Hip strength and wideness does matter.