Unlucky NS, can't comment on the USA match as I didn't watch all of it but Mexico had enough decent chances to easily overcome that handicap..
Lesson learnt would be allthough It seems that sort of handicap would be within reach, once a team gets a 3 goal lead they presume they have the match sown up and take their foot off the Gas defending what they have, especially in competitive match with all to play for, had this been a friendly then I'm in no doubt Mexico would have stuffed Guyana by a hat full.