The Mayweather-McGregor fight is finally here. FiveThirtyEight contributor Brin-Jonathan Butler dives deep on the bout. Could the whole thing be one giant letdown? It's looking more than likely. The lopsided matchup is sending shockwaves through Las Vegas as sportsbooks keep up with the unconventional odds and strategies at play. Everyone expects Mayweather to win easily, but if he doesn't, Sin City could see historic losses.