Local pronunciations are a funny thing.
Here in San Antonio, certain words (specifically places or streets) are obviously from words in spanish BUT they have been "gringo-ized" so much over the centuries that even the local hispanic population uses these "gringo-ized" pronunciations. We have a Blanco Road that everybody pronounces Blank-o instead of the proper Blawn-ko, San Pedro Avenue which everybody pronounces in gringo, and many others.
In fact, one of the funny ways you can tell somebody has moved here from out of town is that they try to prounounce these places in proper spanish and all the locals chuckle at them.
But then there are places that are pronounced with hard spanish inflection like Zarzamora Street or the Hotel La Mansion Del Rio.
So in short if you're from out of town and want to fit in perfectly from the begining - you're screwed.