We see him master the tricks of the trade: how to skim receipts, spot cardsharps, and grease the palms (and more than that) of politicians. Once established, Ace prowls the huge, flashing game room of the Tangiers with the wary omnipotence of a jungle cat, observing the action - observing his life - but seldom getting involved. Technically, he isn’t part of the Mafia, but he has been placed in power by an elite group of Italian-American bosses who trust the numbers guy - the Jew - to up their profits.
Ace, who hails from back East, is a legendary gambler, a genius at working the angles.
As Casino goes on, we see Ace in better days, as he arrives in Vegas in the early ’70s to rule the roost at the Tangiers, a posh casino-hotel owned by the Mob.