To be fair to Fergie, I think he recognised that and never really played him up front on his own, Rooney always had a partner that did the more typical striker stuff under Fergie, he had partnerships with van Nistelrooy, Ronaldo + Tevez, Berbatov and van Persie, it's only since Fergie left has he been used more as a solo striker. When there is another player upfront Rooney's style doesn't damage the team at all, but he simply isn't disciplined enough to play there on his own.