First of all if you haven't done so you should inactivate him. That will help him get back to normal. Might take awhile, half a season or maybe rest of season depending on how badly he was abused.
Many owners, experienced or not, just ignore their minor league teams. Sure, they may not have time to fully manage six teams per franchise. Often they just don't care because you don't actually get anything for running minor league teams properly other than assuring that your players develop best as possible. And sometimes they deliberately short their minors in order to spend their money elsewhere, like on International free agents.
Sucks that you traded for a player you can't use for awhile, but he's not done.