MLB’s playoff format has been the subject of increasing controversy, but league commissioner Rob Manfred is stressing caution.

Already featuring a series of upstart teams in this year’s postseason, the upset wave has continued as the Atlanta Braves, Baltimore Orioles, Los Angeles Dodgers, and Tampa Bay Rays — who each won at least 99 games during the regular season — collectively won just a single playoff game and failed to advance beyond the division series.

Instead, the league championship series matchups of Houston Astros-Texas Rangers and Philadelphia Phillies-Arizona Diamondbacks feature three wild card teams and a combined 354 regular-season wins — the lowest total ever for an MLB final four.