Oliver Wood never once spoke about his skill. Instead, whenever giving pep talks about how great the Gryffindor team was and how they should win each game or the Quidditch cup, he individually pointed out the skills and abilities of each member of his team, but never talked about himself. This indicates that he was very humble and a very good captain, focusing on lifting up the members of his team rather than focusing on himself. Given that he was the only one out of the team over the span of a few years to go on and play professionally (many years after he graduated, Ginny Weasley became the next), I think it's remarkable that he never once made a joke, sarcastic comment, or remark about his skills personally.