Of the eight men in Battlegrounds MMA’s eight-man welterweight tournament, two were the oldest, and two were the only ones who had single-night tourney experience. Naturally, that meant  Roan Carneiro and  Brock Larson would meet in the final. And there, Carneiro took care of business, easily grinding out Larson to win the one-night welterweight tournament and $50,000. “Battlegrounds MMA: O.N.E.” took place at BOK Center in Tulsa. The card streamed via online pay-per-view. Carneiro stalked Larson around the outside and kicked high