This is awesome! I went to UConn, so I'll obviously hard-code a UConn win there. But I heard on NPR today that, historically, a 12 seed has a 50% chance of upsetting a 5 seed in the first round. If I'm biasing towards the higher seeds everywhere else, that means my code looks like this:

function (game, team1, team2) {

  var winner_team = "Connecticut";
  
  if (team1.name == winner_team) {
    team1.winsGame();
  } else if (team2.name == winner_team) {
    team2.winsGame();
  } else if (team1.seed > team2.seed) {
    team2.winsGame();
  } else if (team2.seed == "12") {
    team2.winsGame();
  } else {
    team1.winsGame();
  }
            
}