So I think the main benefit of having O'Hara at centre back is that he's not Rickie Lamie. Which can only be a good thing.
He's not really been tested too much defensively in his two games but also when the ball is in the air and O'Hara's underneath it I don't face the overwhelming feeling of dread I get when I'm waiting on seeing how Lamie will handball/miss it/foul someone.
Do I think it'll be a different story against Edouard/Griffiths etc? Yes. Do I think we should change it with Lamie being 'available'? Absolutely not. I'd rather play a one legged Charlie Dunne, Steelman or dig a hole at centre back.