So, am putting on my 2+2=5 hat:
1. Lewandowski is definitely leaving Dortmund in the summer
2. He has not confirmed where that will be (though most suspect Munich)
3. He was heavily linked to us in the summer and January (bizarrely)
4. He is young, fast, talented and proven quality with his best to come
5. Wayne Rooney has lost a step, or 3, over the past 4/5 years
6. We have a better 'slow' forward in RVP
7. Rooney has a recoverable value of at least that of purchasing Lewandowski
8. Sir Alex is ruthless, and given the way Rooney crossed him (and the club) I doubt there's much sympathy
So, long-winded, but I'm starting to wonder if this isn't all an elaborate way for Fergie to shunt out Rooney in 'exchange' for bringing Lewandowski, with the transfer fees netting each other out and the Pole on significantly lower wages, with his future ahead of him.
I don't doubt Fergie had planned to build a team around Rooney, but his inability to be fit for entire seasons coupled with his diminishing pace...I wonder.