You can certainly see why he doesn't stay very long anywhere, by choice or by design.
I think year one anywhere he will get a reaction by the virtue of him being Ronald Koeman, the football legend. Any player will find an extra 20% to impress a guy with his pedigree. If he brings along a strong work ethic those two combined will see a bounce with any group of players.
Over and above that maybe it's the flip side of the coin. His ego may then take over, relationships may suffer, his reputed love of golf over hard graft and his tactical failings might surface.
You could maybe get away with it a little longer in inferior leagues but here the cracks are showing already.
Nothing to base that on like, just my view.