To quote the movie Moneyball: "Okay, people who run ball clubs, they think in terms of buying players. Your goal shouldn't be to buy players. Your goal should be to buy wins and in order to buy wins, you need to buy your run."
There's no doubt that Neymar is a superb player. The problem I have is not his quality, but whether we actually need him. Lately he's been playing in a central role, and that won't happen as long as Messi is fit.
He would go back to the wing, supposedly, but maybe we don't need more attack in there, since actually we use two full-on attacking fullbacks. This is why Pedro or Alexis are in front of Tello in the pecking order, as amazing Tello is when attacking, he hasn't got the work rate to cover for our often missing full backs. Wouldn't Neymar be a more talented, but also infinitely more costly Tello, who wouldn't play either?
What would that mean for Alba, if he's not allowed to move forward as often, so he doesn't clash with Neymar? Because that's losing half of Alba's talent, right there.