Gary Neville is right. FFP is entirely the wrong way to assess and monitor financial stability. When people say it wasn't designed to stop investment by owners like Sheikh Mansour, that's EXACTLY what it does and appears to be designed to do. What it should be doing is making sure investment is responsible and sustainable. Just looking at the P&L account and adding back or subtracting a few miliion here and there simply doesn't come close to achieving that.
The classic example of FFP is that you can have a club that makes a great profit, say £30m, in one year, then the owner starts to run it irresponsibly and it just breaks even the next. Finally. in the third year, it makes a £30m loss. That club would pass FFP yet just a cursory glance at the trend of the bottom line should be ringing alarm bells.