Having watched him for 20 odd games playing for Pep now, I don't think he was bought for his passing. Stones passing is decent but it's not Boateng or Bonucci good - those long raking balls pinged out to the wing. Don't think I've ever seen Stones really hit a great ball like that, or those long ground passes that cut out the entire midfield.
I didn't like the new Perinau book particularly but I think the quotes from Pep and his team are brilliant and There's a quote in it from Domenec Torrent that talks about how Pep values midfielders in defence because if one of your defenders can beat a man and carry the ball out "with force" then it can provide huge impetus to the entire team to go forwards quickly and break down a defence.
That is the one thing I think Stones really is a class above in. He beats the first defender and then strides into midfield so often and so easily even compared to those world class defenders Pep has had before and I can only think that's the one thing that Caught Peps eye compared to other players we could have bought with that money.