He left shortly after Ryoma and that was the only time he could've left. Each team had to submit a new player list before the Finals Tournament, but they can't change members in-between rounds. So Ryoga had to leave before the 1st round. I don't see why he'd care whether America beat Switzerland.To add. Ryoga left before the Swiss Vs USA match.
Obvioulsy Ralph left them for Switzerland to have a better chance beating USA. But his plan failed. Usa pull up an upset against Switzerland.