"So had the scores also stayed the same when 10 played 11 yesterday, Villa would have won 1-0. Plus, there is considerable difference between losing a nippy winger with 61 minutes to go and the most experienced centre-half with 86 minutes to survive. To replace Vidic, United would have had to introduce Wes Brown at the expense of a midfielder: Ji-Sung Park, perhaps, or Antonio Valencia, who set up the winning goal and won man of the match. "
Samuel is dead right. Imagine if Valencia or Park went off after 5 minutes - it would have been a different game.