If someone is quite good at boxing, chances are they are going to be able to fight for real in the street, I've seen guys that would own me in the street, but when they walked into my boxing club, I would serverly own them with the littlest of ease. I've yet to see a good boxer fail to proform on the street, doesn't mean they will be as good as they are at boxing, because it's a totally differnt thing.
As to my boxing skills, I'll post proof when I get my harddrive pluged in again.