He was talking about the fact that he left a team that needed rebuilt. The catalyst for that last title, as much as everyone credits Fergie's will to win, was RVP, who Utd deviated away from their policy of buying younger players, who Utd would get their prime years from.RVP was brought in to win that title, and he did, after that not so much. When you look at the team we had that beat City 3-2 in that last title winning season:
De Gea- still here
Rafeal - left 2015
Evans- left 2015
Rio- that was his last real season for us
Evra- left 2014
Valencia - still a winger then
Young - still a winger then
Carrick - still in his prime
Cleverly - left 2014
Rooney- stayed
RVP - one great season, left 2015
there were other players in the squad of course, but just that 11 that day, 6 of those players were gone within 2 years, 2 of those who stayed ie Valencia and Young were then converted to full back as they weren't able to play on the wing anymore