I don't see any noticeable flaw on Anderson's game, I see a noticeable worst part among other superb parts in his game. If we both agree we are speaking about his wrestling, it's not a flaw to be under Chael Sonnen for your whole life. Everybody stays under Sonnen... It's to compare the worst of Anderson with the best of Sonnen.
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His TDD in general is pretty bad, as seen in thhe Hendo and Lutter fights aswell. It's the key stand out weakness for him, but unless you have the ground skills of say Sonnen or GSP you won't be able to hold him on the ground long enough for it to be a big moment.
EDIT: Pretty much what Canadian Psycho said, although it's well seen that I don't rate his submissions quite as highly.