Love your first sentance deffo reusing that if you don't mind
I've been saying this (that net spend is a meaningless metric) for ages. My analogy involves two people going into a Porsche showroom, one with a 10-year-old Ford Focus and the other with a 1-year-old Porsche. Both trade their cars in and come out with an identical new model.
The net spend will be hugely higher for the former than the latter, but they've both got exactly the same in the end. It all depends where you start from. Also the longer the period you're comparing it over, the more inflation comes into it.
It also doesn't take into account (over a short period) players who need to be replaced. So if a player leaves and you spend £50m to replace him, that's a £50m net spend if he leaves at the end of his contract. If a player leaves 3 years into a 5-year contract and you get £30m for him, that's a £20m net spend but you're in exactly the same position, as you've replaced one player with a £50m one. There's no context in a bare net spend figure.
There are at least 3 better metrics to make financial comparisons with.
- Wages plus amortisation
- Total squad cost
- 'Free' cash reinvested in the squad (that is, how much actual cash, after paying operating expenses but including player sales revenue, do you spend on new players)
All of these are quantifiable from club accounts (although that last one takes a bit of work).
One example I uncovered from my analysis of the so-called 'big 6' accounts is that Spurs, up to relatively recently, only spent on new players what they received for outgoing players. Whereas all the other five clubs used additional cash generated from their operations (and we generally generate £100m or more from ours, which we fully reinvest).
The only time net spend would be a factor in a club's calculation is when they decide they've got a fixed sum to spend in a window, and any additional spending will have to be financed by player sales. But that will be a season-by-season, even window-by-window decision.