This is the only thing in the entire Fallout 4 game that really bothered and still bothers me, they cut the arena and there is even cut dialogue for Tommy, that suggests you could bet, and of course fight, after some digging my self I even found out there was to be a use able merchant that was cut in the Combat Zone as well , named Patches. I am prepared to compensate who ever can do this task, through paypal or donations, premium account on the nexus, or even a game of your choice on steam via gift, if you so desire it, It would be worth it. Add me on steam for more info, http://steamcommunity.com/id/THERECANONLYBEONE/