I can't read Spanish too well, but it think the article claims he's coming off a major knee injury
http://www.elporvenir.com.mx/notas.asp?nota_id=53214
I would guess the highest level of Mexican football is well below D-3 in the U.S., as every year our D-3 types (minus the few D-3 NFL prospects) beat Mexico's best in the Aztec Bowl....
http://www.aztecbowl.com/
My guess is the NFL found him in the Aztec Bowl whenever he played.