Just four of the United starters that night are still at the club with Danny Welbeck, Javier Hernandez, Anderson, Shinji Kagawa, Marnick Vermijl, Saido Janko and Reece James also being sold or loaned out.
"It was a bad night for all the players. I do think if the result had been different, things might have turned out differently for some of the players, if not all of them," said Keane.
"When you play for United you don't get too many chances. When you do, you have to take them and a lot have moved on, myself included, since that game.
"I think a lot of the players were disappointed with how they played that night. I was gutted for a few days afterwards and really disappointed with myself, we had a debrief the next day and I was hopeful I would get another chance but it just didn't happen."