"Rebuilding the squad" can be broken into different bits.
The easy peasy bit is "getting rid of dead wood" and "cutting the wage bill"; you simply don't renew contracts or you pay people off. You don't need to be a managerial guru to do this and yet he has received a lot of praise for doing so.
The difficult bit is replacing, shaping and motivating. This will be judged on, to a lesser extent (and I am being generous here), performances but ultimately on results. To do this bit, you DO need to be a good manager and he has fallen way short. Subsequently, this and, considering his abysmal lack of anything approaching people skills, was only ever going to end one way. Better now than later in the season when things would probably be even worse.