He could have won that fight. Plot restricted everything he had including the Rinnegan & Mokuton. He's not weak - Obito's Eye is superior to Kakashi's so him having the Senju DNA won't do anything.
The fact that the Uchiha clan got its butt kicked by the senju who have no direct battle advantages means that the Uchiha generally depend on their eyes WAY to much. Obito is no exception.
