I wouldn't really read much in to what happened in the last twenty as I can't see how Welbeck/Rooney is much more different to RVP/Rooney in terms of approach, for me the key factors were getting the second which killed off West Broms hopes with them visibly declining after it and the confidence boost it gave us. If anything Rooey dropped slightly deeper and worked stuff better from deeper which allowed carrick, fellaini, mata and kagawa to really get involved in the build up and that's a key thing we've been missing in most games.
I'd say the bigger thing about the last twenty is not the issue of RVP/Rooney but the difference between Rooney playing too high and him playing deeper and more patiently, with the latter allowing players to get involved much more and for us to progress centrally. When he comes back and either passes it back or sends it wide and then runs back up the pitch it doesn't do much for us, but when he passes it, waits for the return etc then all of a sudden it opens up options. That's what we need him to do with RVP on the pitch.