It has something to do with the facts and the law and who the judges are. So I think lawyers sometimes exaggerate their role in winning and losing. Lawyers do have a role, and a major role, but they're not the only players in this game.
I used to watch him practice. It was a sort of Jimmy Stewart style. Denis was a very soft-spoken, self-effacing, overly modest person who left many flashier lawyers in his wake as he persuaded judges and juries alike that what he said could be trusted and should carry the day.