Basketball isn't big here, dude. Sure the NBA is on ESPN Deportes once and a while and I saw UNAM play Indios in a Basketball game but not only were about 90% of the players foreigners, but Mexicans, traditionally, aren't very big. I'm the second tallest person in my dorm building a the UDLA Puebla and I'm 5'10. Generally, most basketball players are fairly tall.
American football is growing here, but that isn't because people actually like the sport, it's because of the infeority complex with the United States, and everyone wants to look cool in the eyes of a "gringo" which isn't exactly going so well. Even the players here don't understand the game, I watched the Superbowl with a few guys on the team here that live with me. They went nuts at an incomplete pass, jumping up and down screaming "fumble fumble fumble" as loud as they could, and looked confused when I told them the rules of the game. It's more of a way to look cool and blend in, if anything.
And I disagree with you on the fact that you think the economic situation isn't part of the reason the game is popular. Get your ass out of Chapultapec, Polanco or Reforma and see things from the street level. The people here are poor. Very poor. With the exception of a few people, this country is very much third-world. Out of the 105 million people here, I'd venture as far as saying that 80 million of those people are living in poverty. When you've got as many pobres in the streets as Mexico does, you would think it's a bit hard for a youngster to buy a few racquets and get started on tennis. Tennis is a middle-to-upper class sport, and the fact that a middle class is non-existant here just adds to that. The rich kids that study where I do just don't care about the sport, and the ones that do either suck and just worry about looking good on the court, or are too old to accomplish anything (the #1 and #2 players at my university have a combined age of 59). The game isn't seen in the same light as soccer down here, which is strange because Mexico isn't that good at soccer either.
The players are there. Mexico had a kid reach #6 in the ITF Junior YE rankings last year, and there was a kid in the mid 30s or 40s as well. Not too bad.
Tennis will come good here, as soon as the corrupt are removed from office, middle and lower-class families realize that having 5-7 kids isn't economically sane (overpopulation leads to less money being circulated and with more money lying around then you've got a higher chance of a kid playing a costlier sport), and the drug cartels stop hogging all the money.
If anyone else wants to hear more I'd be glad to elaborate.