the 4th was strong but he could not defeat any of the sannin i dont believe. he had his sealing jutsu but , remember the reason Oro wasnt chosen to Hokage was because of his dark side. Oro wanted to be Hokage because he was sure he was the strongest...and the things the 3rd said tended to support that. as for Oro not being able to touch the 3rd in his prime...hrmm possible but Oro had such a superiority complex going until he was caught that i dont think he was fighting his hardest..actually he wasnt he was letting the first, and the second fight in his stead. However i am inclined to believe the 3rd was stronger when he was at the same age as Oro