If you are going to compare anything that's easily accessible, it has to be wages. That's where the big money goes, and it reflects the players you have.
Net spend has so many other factors, and us being "mid-table" spenders, proves it's bollocks, as the more successful and settled a club is, the easier it is to keep net spend down. Our net spend was obviously horrendous when we were trying to catch the rich clubs after the takeover - now we can sell players for high prices, and just being on our books adds a premium to sales of young players.