There's been a pattern in most seasons where the team that finished first in the next to last leg, is second in the final leg, and obversely, the team that finished second in the next to last leg won the final leg.
Given that Max and Katie won the three legs prior to the final leg, it's fair for CBS and Phil to call the winner "surprising"; however, Bates and Anthony had the best average placement of any of the teams in season 22 (2.4166) and would have no matter how they finished the final two legs aired tonight. (Max-Katie's average was 4.2500, and Mona-Beth was 4.3333.)
And I believe this is the first time two teams of athletes finished in the final three (Don't forget that Mona-Beth are professional roller derby players.)