I think we are underating obi-wan a bit. Anakin may beat him (just) in saber combat but there is no way or evidence that he would ever outrank obi-wan in force ability. The only thing Anakin can do with the force is to choke padme half to death.
Besides I wouldn't call Anakin un-focused against obi in ROTS , I would call him enraged. Obi-wan wasn't exactly focused either, he was blinded by emotion and anger.