I work for the company that own Opta. They make money from selling the stats to broadcasters, yes, but their main market is they sell to the individual leagues/organisations, which distribute them to the teams, who use them - along with their own levels of tracking - to gauge player performances.
Nobody is saying that it should be taken as gospel.
But they are used to help see how a player is performing.
People shouldn't say 'he was anonymous' without knowing that they can back it up?
You mention key passes.
The biggest criticism of Gylfi is 'he doesn't create enough', which is absolute bull, because he does create a lot - he's our most creative player.
On Sunday, he was - by definition - the most creative player on the park. That creativity didn't lead to a goal, which is part of the problem.
Another is that he's slow, yet he was averaging our highest speed...
I'm not suggesting he doesn't need to improve. He didn't have his best game, but the stats show that he was still one of our highest performers in a number of areas. So does that say more about the team or Gylfi?