I was impressed by this article on marginal advantage by Sean Plott, who among other things is a high-level competitive Starcraft player. It discusses some more general points, suggesting that “a good competitive game should test a player’s skills and minimize the element of chance”, which I agree with, despite my long interest in Magic: The Gathering.
I also agree with his corollary that in a good competitive game, “the probability of a weak player defeating a good player should be as close to zero as possible”. Notions of “weak” and “good” players here should be as diverse as possible.
I’m not sure how this applies to tennis, the game I’m currently most interested in, but the winner of the match is often not the player with superior strokes.