Wayne Rooney without doubt had a very career as a player, but that's absolutely been the opposite with his managerial career and I think it's be better for him not to continue with the profession as he's failed in almost all the previous attempts.
This shows that the fact that a person is good at something doesn't mean it would be easy for them to teach others.
But if we look at the case of Rooney, we'll see that all his colleagues who have tried managerial careers didn't excel at it. From Phil Neville to Ole, Rooney, Carrick, and so on. I think the issue comes from the top, Sir Alex Ferguson. He was a good coach no doubt, but most of his students have not had any decent season where they won a silverware convincingly.
They still want to play the traditional pattern of football which was played in the 90s but they forgot that football has evolved passed that. That is a reason Mourinho is struggling today. If you can't press in today's football your team would suffer, especially against teams that can press.