By Avi Creditor Wales, England and Iran are the three opponents, and while it seems manageable on paper, it also arguably makes for the most difficult quartet in the competition. Suffice to say, the group stage that the U.S. men’s national team is about to open up is hardly a tune-up for what’s to come in November. The Concacaf Nations League, where the U.S. will play the world’s 170th-ranked team (Grenada) and 74th (El Salvador), begins for the Americans Friday night in Texas, and it’ll seem a world away from the World Cup—even if Austin’s Q2 Stadium is where the U.S. edged Qatar in the Gold …