Finally got to this Ball Square Mexican/border food joint. It's a decent, casual, neighborhood-y kind of place, a mix of Tufts students and locals, the game on three TVs. An excellent queso fundido with chorizo, good guacamole, a very nice chicken enchilada with red sauce, a good fajita plate. Nice prices: $9 for a three big, chicken-stuffed enchiladas with rice and beans.
Disappointing margaritas, though. I'm kind of tired of paying extra for good tequila and not being able to taste it. I guess it's like mixing good whiskey with Coke: I should just get it neat. And yet the East Coast Grill, Audubon Circle, Green Street Grill, the B-Side, and Tremont 647 all do outstanding margaritas that justify their tequila-upgrade premiums.
Service was a little distracted, not enough to annoy. We stayed to the end of the game, then fled once the karaoke started (some spectacularly bad singing).