If 3 players are tied with the same record, they go by sets won. If 2 players are tied with the same record, they go by H2H.
I think we determined yesterday in the Red Group scenarios thread that it's not quite that simple. We never really fully clarified it because the rule is a bit confusing but it starts with sets won and then may go BACK to head-to-head if sets won can eliminate one of the three players.
I guess we might get insight into what will happen next year at RR competition. then again, unlike an IS tourney, a win here is worth $120,000. I'd try for that kind of money