This.
People called it early doors though, he was replacing players with purpose for multiples of the same position (Rooney, Klaassen and Sig) and spent mega money doing so. Now he feels inclined to fit them all in, at all costs. That cost at present is a working formation.
I wasn't overly sold on koeman, he improved with his conferences but he's showing exactly what happened at Southampton. Falls out with players, Can be very stubborn and favours particular players. It's not looking great.