He usedto be a member of one of the gangs in the shades, yeah I'd say so. Takes a crook to catch a crook etc. Perhaps being streetwise should be one of the Gangster's talents: knowing the right back alley to get away, knowing just the right guy to talk to, knowing just which doorway to ambush someone from. A real "Ranger" type class, but for the streets. A cop is just a member of a gang that calls themselves the police and gets protection money from the guv'ment, after all...
And yeah, strikes that reduce speed, give attack penalties and even daze a target would be perfect: shattered knees, broken arms, heavy blows to the head... Lots of lovely dirty tricks that don't deal much damage but really penalise a target...