Well, we're mainly in agreement about Castro then. He played his first game for the Twins when he was almost 26, so we're talking about his development by the Tigers, and he played about 90% of his minor league innings at SS so the Tigers apparently tried to teach him, but it didn't work.
That's the thing. "Nobody learns a position in the minors" doesn't take into account that the talent and aptitude just might not be there, no matter how hard you try to teach.
Fair enough, so then I'd still like to know what (and who) prompted your post. I laid out in my reply that the current 26-man roster can't really be the cause of such a sweeping indictment, since most everyone except Castro, Martin, and (to the small degree he's been in the majors) Lee play pretty normal rotations.
Lee is the only one who might qualify, since IMO Castro and Martin lack the apparent aptitude to become really good at any important defensive position. The Twins FO gets regularly dinged for being slow to promote, so it's ironic if they move Lee upward quickly, only to be hammered from a different direction for not completing the development process.
Also you single out the Twins, but as mentioned above Detroit with Castro may fit this same mold, so is our team really out of step with standard practice across the majors these days? Honest question there (as are most of my questions when I'm not kidding around, I hope).