The question about Costa Rica isn't why they're down. The question is how they did they stay up for so long.
Jamaica was resting their starters. And they still created enough chances to win if not for piss poor finishing.
You can say off of form. If you want a definite answer you will see at the World cup in November sure, but anyone can see that Japan has grown immensely in player pool and quality in the last 2 years the amount of youth in Europe, and general oppressiveness of how they play in possession. Iran has Azmoun and Taremi up front now(Russia and Portugal top strikers) with a lot of depth as well. Most players in Europe they have ever had. Saudi has been playing some fluid football. Qatar, South Korea, and Australia have stagnated since the Asian cup. Now yes Qatar is to be called the Asian cup champions til the next one, but no point pretending they havent stagnated while others have improved.
Mark-Anthony Kaye committed maybe the single-stupidest foul for a correctly-called penalty that I can remember in ages. Canada were very, very fortunate to dodge a bullet...
Mexico just isn't very good. Tata Martino has no real magic left for this side, I don't believe. Mind you, I would not be shocked if they beat our second team by multiple goals, but this is not a great side...