Guys like Martinez are rare, he doesn't do instructional league, he goes back to run one of the leagues in Nicaragua, in fact the cardinals don't do instructional league anymore. I am not sure that's a good thing, but they don't, they stopped doing it a few years ago. I think the Marlins did too? They do have camp for rehabbing players. They would rather move players up (some college guys actually have moved 2-3 levels sometimes in a season and head off to winter ball if the need work) and the young latin players are headed back home to play.
There must be a reason, (if it is the player I am thinking of), he didn't sign until late and never played in 2010 (JUCO player), and did extended before GCL began. That meant he had plenty of instruction before he started playing this season. It might benefit him for sure in more ways than one, but everyone has their reasons for why they do and do not do things and should be respected.
Maybe he's just burned, this is a tough job (yes it is a job),reality is, it isn't for everyone.