mmm I like the shape you use for the crest in general, looks really retro and I love that; I would change MEXICO for FMF (because of Federacion Mexicana de Futbol) and well... also Mexico has a mistake it´s México (how the original fail on that too???!!! fuck!!!)
But, maybe the real problem here will be the national coat, as buttplug said, can't be used for this kind of things, only goverment issues and flags, that´s all, of course you probably didn't know that and it's normal (actually not all the mexicans know it ¬¬) your are not obligated to know it
I would like to see one more with a prehispanic style, maybe in other opportunity, but really really love the shape and golden details
I have to agree though, something doesnt seem right about this crest. Looks quickly put together and it doesnt seem to follow the present crest. Ill wait and see your next try though. Keep up the good work!