Fowler was and still is wildly overrated. Productive, yes, but bad defensively, at times so bad that he didn't make up for it with his offense. That's the guy Murray should've sold high on, but he instead signed him long term and let Theodore be the sacrificial lamb, which was obviously a mistake.
But as Henchy pointed out, it's not the biggest nor only mistake they've made--they're a terribly-run organization and have been for many years. The only GMs I'd consider worse than Murray are Benning (and that's debatable) and Gorton (not debatable).