This.
I think many are looking at PSR all wrong. A lot of people seem to think that clubs are judged by their relative distance from some arbitrary figure that's set at X and is equal for all clubs. So, how can ManU and the like spend so much more than us without breaching?
But we have to remember that everyone is not being judged by an equal X amount, because that X is set differently for each club relative to its revenue generated. So ManU, etc. just have bigger Xs than we do, because for many years now we've been run so poorly as a business that we make a pittance in revenue relative to the other big clubs. Our commercial department definitely has to be the worst among them.
The simplest solution to the PSR problem doesn't even involve player trading at all. It's to grow the commercial side of the club as much as possible.
* My understanding of the City issue is that they're not in hot water over straight profit breaches of PSR but over fraudulent behavior, lying, etc. So it's a different issue to this altogether.