He would have properly used Ronaldinho of course.
By benching him!

Ronaldinho would be exactly the kind of player Mourinho wouldn't want in his system where he would more than anything be a liability.

Obviously if it was the world player of a couple of years ago, I'm sure you could find space for him somehow but the recent lazy underperforming unfit doing more harm than good shelf of a player, he would strongly resist getting to the club.

And I'm sure whether buying a player like Ronaldinho or not, has been one of the reasons for the various fall outs with Abramovich.