It sounds as if AMC's executives are great at being entrepreneurs (getting/picking new ideas, getting those ideas started) but terrible at being administrators (long-term planning, the grind of actually dealing with talent/employees). It's a common problem in business, actually.
I'm sure many will think AMC's previous executive choices were luck (talent falling into their hands), but being an entrepreneur is a very different skill-set from being an administrator. It wouldn't surprise me if these guys really are
great at picking new shows and getting them going. They just need to hire better people for everything that comes afterwards.