Probably time to shut it down. You've replaced 50% of your GM's and only simmed one season. I could give you some reasons why you may be having difficulty in private if you want to hear them. If you are getting frustrated, then just participate in other leagues and let other Commissioners do all the work. There are so many good leagues out there - more leagues than players, really

If you really want to be a Commish, go with a smaller league. I really think smaller leagues are the key, 20 teams or so.