I don't recall any age questions from back when he first signed.
Later on the Mets didn't seem too thrilled with his conditioning/work ethic as 'Supersize it' appeared to be among the first English words he learned during the downtime he had waiting for all the immigration snafus solve themselves.
He got in better shape once he got back into things and had that real good start in Arizona (CG, 2-hitter) - but that was his peak and once they decided he wasn't going to make the rotation the following Spring he was released rather abruptly without seeming to even be considered for the pen. Nothing specifc was ever said but, again, you got the idea they weren't high on his effort.