What I'm saying is that let's say Coutinho is worth £100 m Keita £40m Fabinho £20 m Shaqiri £15m (I'm sticking to midfielders for the point to be clear). Im just making the numbers up and it's not specifically about pool, just the issue itself.
Player lost = Coutinho (+£100m)
Players bought = Keita, Fabinho and Shaqiri (-£75m)
If you ask Klopp or any manager if he would prefer to keep working with Coutinho or Keita, Fabinho and Shaqiri, what would you think he'd say? He might say one or the other, I don't know but some would say that ONE Coutinho is worth more than those other three together because he's so much better than the other three, hence the price, hence the net spend.
Now, of course it's not always that simple as you point out with Sanchez and so on. Another thing is, you can sell a really great player and buy several not as good players but still make the team stronger (like pool). It's complicated but as a rough instrument, net spend says something, maybe a lot.
