I've always been curious why backfists are illegal in boxing, but I've never really bothered looking into it. I mean it's not a power punch. It's only a setup that's weaker than a good jab or straight left. No one's going to get KO'd with a backfist, so why make it illegal? The only thing I can think of is that it has something to do with the glove being thinner at the area where your backfist and knuckles are.