As an example, just rewatch the set piece goal, and concentrate on Mangala - then tell me he isn't partially to blame for that goal. That is defending a corner so nowt to do with Sam's formation.
You cannot absolve the players of blame - most have been terrible.
Thankfully it's not an either-or situation: some of the players are shit and the manager is shit too. Not least of all for picking the shit players even when he's got other options.