I don't even know what that's supposed to mean - not fighting like a true champ. Weird thing to say.
You know what the hell it means. It means getting in there and using your skills, not some underhanded tactics and blatant disregard for the rules to win a fight.
It's Berto's fault for not knowing how to deal with a physical fighter. He fought like the gatekeeper that he is.
Look, you aren't going to get me to disagree that he isn't a gatekeeper. He is, but it wasn't just a matter of the guy not handling a physical fighter. If you're using a style you NEVER used before, and that style is basically WEAK against a southpaw/unorthodox stance, you're asking for trouble.
True champs don't rough people up? Watch Jack Johnson, a young Hopkins, even Floyd has his tactics.
There is a difference between roughing someone up and fighting dirty. Get physical, get rough, but don't fight dirty. Don't lead with your fuckin head, don't try to thumb a guy in the eye, don't keep hitting below the belt and don't keep clocking him after the bell rings (over multiple rounds.)
You know the rules of the game man, you know when a fighter is going over and beyond what is called for.