Have to agree with Mad Winger here.
I agree with you that you can't blame van Persie for the other guys' failings, but when you state the signing of Kagawa was a mistake, I simply have to disagree.
For me, Kagawa fitted in perfectly to what we had going for us with Welbeck and Rooney; van Persie didn't.
I think Kagawa would have complemented Welbeck and Rooney in an attack given time to gel, whereas I always thought van Persie wouldn't. I've never seen him as someone who plays well with others close by him - "In his areas"
Signing both in the same window was silly, in my opinion, and it just demonstrated a desire to regain the title from City that year, even if it would set us back after and leave a few problems. To win at all costs. "As long as we won" I think Evans said.
We actually didn't need him. The problem wasn't actually there to be solved. And I think there were other motives behind signing him beyond improving our team, personally.
It worked, for that season.. But I think we could have won without him, and would be in better shape now without doubt.
I'd definitely go back and stop us signing van Persie, and spend that money on a midfielder, if I could go back. Even with the knowledge that he'd play a big part in number 20.