Ronaldinho Gaucho is regarded as one the greatest football players of his generation, so to say that he did not live up to his potential would mean he was destined for even greater feats than he already achieved.
There is a lot of pressure on football players to be perfect or to live up to some expectations set by players such as Cristiano Ronaldo. Not every player will be as perfect as Ronaldo. To say that someone is not living up to their potential implies they are being lazy or not putting in the effort. This is not true of Ronaldinho.