See, here's the problem... there is more at play here than just simple wins and losses and cross-border rivalry. From a pure rivalry standpoint, the US could have just let Panama keep their 2-1 win, playing passively since the US not only qualified already, but clinched the group win. That would have allowed Panama to snatch the playoff spot away from Mexico and heap loads of embarrassment on our key regional rival.
But there were a couple of extra factors in play as well. First off, for the good of CONCACAF, you want to make sure you have the best chance of winning past this stage, because past performance goes into determining future World Cup berths. Mexico should get past New Zealand, because it's damn near impossible for opponents to score in Mexico City, so even draw-draw in the two-leg playoff would at least give Mexico a 50% chance on PKs. Panama... well... clearly isn't a dominant home side.
Secondly, the US had an outside chance of making the top 8 in FIFA world rankings, which would give them a seeded spot for Brazil. A loss to Panama would have ruined that (slim) possibility. Again, whomever plays New Zealand (Mexico now) might affect that ranking as well, if I understand the formulas correctly.
Well, I think it’s ridiculous that England literally has to win every single game in qualifying to get a spot in Brazil, while Mexico can win 2 out of 10 games in the weakest confederation on the planet and still get in.
In a fair world, CONCACAF would get 1 spot in the World Cup, that’s it!
There is a thirdly - the US players want to pass the cut and be on the team in Brazil.