The most important part of the article, I think:

"“Eurisko was exposing the fact that any finite set of rules is going to be a very incomplete approximation of reality,” Lenat explained. “What the other entrants were doing was filling in the holes in the rules with real-world, realistic answers. But Eurisko didn’t have that kind of preconception, partly because it didn’t know enough about the world.” So it found solutions that were, as Lenat freely admits, “socially horrifying”: send a thousand defenseless and immobile ships into battle; sink your own ships the moment they get damaged. ".

Lenat, Lawrence, David, and the basketball girls all 'played' in a way that emphasized their own strengths and took advantage of the limits of the situation; they refused to accept the conventions everyone else held, and so they were able to beat them.