Not neccessarily, the legendary Hugo Sanchez, Guardado and Marquez off the top of my head all came from the Mexican League. Its just like anywhere else, if you look hard enough there are some very good players there. Generally its easier to spot strikers because obviously they'd be scoring for fun, but then there could be a world class full back or DM over there and you'd never know because they wouldn't stand out as much.
Proper scouting and a bit of a gamble can really pay off in those American Leagues
I've watched a fair bit of it and been to a few games. Trust me, its crap. Even the Mexicans would tell you that.