Personally I think Koeman biggest failing is his inability to set up aside without a proper targetman.
I think things would have been quite different if we'd recruited his 1st or 2nd choice.
Rooney could play number 10 and drop deeper like he does now and not leave us with no one up top.
All these nice shiny new#10s would have someone be to play off.
Cuco M would have someone to aim his crosses at.
Until we get a proper striker for Koemans tactics we're gonna struggle.
No one can fulfill that role properly from the current squad and Koeman can't adapt his system to get it to fit HIS players.