I am mystified at how KROQ thinks that a genre of rock that gets virtually no airplay anywhere in Latin America and sells even less will be popular among anyone in LA.
Hispanics in LA are hugely and predominantly from rural and small town areas of Mexico and represent an audience that has little exposure to rock, which in Mexico is mainly heard only in larger cities and is generally more mainstream in nature. Oh, and most rock played on the radio in Mexico is from the US and in English, not in Spanish.
In fact, the only successful Spanish language rock station in Latin America is way, way south in Argentina where, in fact, it spent its first 6 years at #1 in that larger-than-New York City market. But Buenos Aires is essentially the southernmost city in Europe, so that station and market can't be used as examples.
Travelling through Costa Rica last year I was surprised to discover one of the better-sounding alternative-rock stations I've heard in a while, oddly calling itself "Radio Hit." The morning hosts spoke Spanish but there were no Spanish language songs at all, and no rhythmic "hits" as the CHR-sounding name suggests, but all rock-based stuff.
I wasn't even aware that rock and alternative music had a strong enough following in Latin America to support stations like that. But you're right, Spanish language alt/rock songs were absent on a station that you'd think would be in the best position to play them if there were any interest.
I think it's a national station with sync'ed transmitters on 104.7. We did a lot of travelling around the country could hear it everywhere we went on that frequency. http://www.1047hit.com
Stream : http://www.1047hit.com/player.html