That proves that it doesn't even matter how good history in your career as a footballer and there is no guarantee if you will be a good coach. In fact, so numerous players that shifted to be a new coach were only a few that was successfully become good coach.
A general pattern. There are very few former world-class players who have become successful coaches. Most of them have had one or two stints as a coach and then never found a job as a coach again. Wayne Rooney is also very unlikely to become a successful coach. Much more successful are former players who have played in the first or second division of their country, but have never really been among the greatest. The best examples of those are Carlo Angelotti and Jurgen Klopp.
It's different between coaches and players, so coaches have nothing to do with a person's career as a football player and there are even some great coaches who are not basically football players.
Regarding Wayne Rooney not being successful in his coaching career is not a big surprise, we have also seen many previous examples where someone had a good career when he was actively playing football but not when he was a coach, such as Pirlo.