Winning games, whether exhibition or not is always a good sign for any team. They can build off exhibition wins and mentally will know they have what it takes when the games count. It will help confidence out tremendously to beat some of the worlds better teams as well. The games still need to be played though, so we shall see.
Since this topic is coming up, I'm going to say that our team is not good. If the team has used their time wisely and aren't convinced they'll be able to win with minimal training, then yes they will have what it takes to win when the games start to really count.
Some will argue that exhibition games don't really matter. This is not true. Even if it's just for a psychological advantage, especially since Mexico didn't even score! But in the US exhibition win over Mexico, the US showed serious talent that was lacking on Mexico's side, making them a favorite for when the regular season begins.
Yes it does. Since they won when it counted this time it shows that they have the potential to do it a again. During the game against Mexico the US came out on top under pressure. The US had to put in extra work to win that game so they should know what they need to work on for the next game.