Any player will be unsettled by the situation John Stones finds himself in.
One minute he is settled at Everton looking forward to the new season, the next he is on every news media reporting that he will be sold to Chelsea at various prices. There have been two definite bids that we know of and probably definite enquiries from others as well.
I am sure his agent would love the big payday a transfer would bring as well.
There is no point in saying it hasn't affected the player, but that doesn't mean the situation has changed and the player is for sale.
After Sept 2nd everything will settle back and the football will take over again. I think he will probably leave summer 2016.