United bought JSV to help us in Europe, not to replace Scholes.
Barca aren't committing any mistakes, they won the treble last season.
I would agree that a player of his quality won't be happy sitting on the bench too long, and hence Pedro is looking for a move (or at least what we have been made to believe). I have never said that there is an issue with his signing.
Coming to the second paragraph of your post, because a couple of high profile signings failed to shine, it doesn't mean that we should stop looking for them. We also bought VP and he worked like a treat for us in Fergie's last season. Barcelona failed with Zlatan, Cesc and Sanchez but won the treble with goals from Neymar and Suarez. Not saying that one player would change the entire system or single-handedly win us titles, but top players do help you to get closer. You need that special quality to help you or bail you out at times. Pedro as good as he is, and as well as he would fit in the "system", isn't that player. Again not saying that we should pass on him because of that, just that the addition of Pedro will still leave that gap in the squad. We could close that, e.g. with Pedro plus Lewandoski, or some other top striker. Or a Bale or Ronaldo can help close that gap.
I think the 'prophet' is as widely recognized as he should. The thing with stats is that you can have as much fun with them as you want. Someone would look at them as 100 goals in 300 odd appearances, someone else could look at them and say that nearly half of them were scored in two seasons, the last of which was four years ago. They are useful in a way, but nothing like the opinion you could form after watching a player.
I think he would score more goals than di Maria, as he is more of a wide forward. Though he only partially solves the creativity issue, which was one of our major concerns last season.