I think one thing that people seem to miss is that Sidious created the lightning, that despite being absorbed by Yoda, ended the duel. From that explosion, Yoda came off worse. People say - "It was luck that saved Sidious and had Yoda fall". I think that couldn't be further from the truth. Luck, in essence, doesnt really exist. For me its about cause and effect. Sidious created the lightning, Yoda fell off the pod. I think the reasons for battle were obvious as well. Sidious was forced to do battle (after he thought he could kill Yoda easily) but all he had to do was survive by 'dealing with Yoda'. Yoda had to win. He didn't. He failed. That's why I think its completely fair to say that Sidious won and Yoda lost. Its what happened!