No in the commentary Lucas himself said that by turing to the dark Anakin became a better lightsaber dualist than Obi-Wan, in terms of sheer power Obi-Wan was far from the most powerful, the Midichlorians kind of decide who the powerful Force user is .
Well, to be honest relying on commentary to fill in such gaps is just poor storytelling. Besides, does he explain why in an in-universe logic sort of way why that should be so or even make sense? It just seems like more of the same moronisms that seem to come out of him. If all it takes is you go and dark you become a better swordsman - how can the jedi compete against that?
Seeing as how both Obi-Wan and later Luke was able to beat Vader(Of course Luke had some help from the Dark Side.) there is a way, but then Kenobi was able to beat Darth Maul and Grevious I'd say his secret lies in his defensive use of the Force for his lightsaber combat skills.