If I was a GM I'd have no qualms about hiring a manager who's never coached in the big leagues. There's been lots of successful managers who never "paid their dues" by starting their coaching career in the minors. If he's ready,he's ready. Michael Young has sat in a dugout watching a manager since he was in grade school,probably thousands of games. Just not sure he has the personality/mental make-up to be a manager.
If I was a GM, Id have no qualms about hiring a manager whos never coached in the big leagues, either, but not one who doesnt have the right mentality for the job or any apparent interest in becoming a manager.
Even a former player who does want to become a manager but has no experience might not be the right fit.
The number of former players who can be hired as a manager with no experience and be successful is small. The number is even smaller when you take into account the talent the Rangers currently have.