Fred Cantu's Mexican Radio and TV website lists 1550 XEBG Tijuana as an ESPN Deportes station.
www.mexicoradiotv.comThis website is usually quite reliable, although the logo next to the listing says "DOC Radio" so maybe ESPN Deportes isn't on 1550 anymore?
800 has improved its coverage north of the border. According to Radio-Locator.com, the 800 signal has been upgraded to 1000 watts non-directional at all times. They used to be 500 watts by day and even less at night. I guess they don't have to protect 800 XEROK Ciudad Juarez, which had been the 50,000 watt clear channel station on 800.
The upgrade from 500 watts day and night of XESPN (formerly XEMMM) to 1 kw day and night was made possible by the relaxation in Mexican rules as well as the fact that the new power of XEROK is 50 kw, down from the historical 150,000 watts of XEROK and its predecessor, XELO.