It was reported by the British newspaper that Everton had rejected a bid of around £30 million for the 21-year-old, who can also play as a right-back.
Stones’s performances this season have been not great, with his propensity to take too much time on the ball in defence criticised by fans and pundits alike.
Former Sky Sports presenter Keys has suggested that Everton manager Roberto Martinez should have allowed Stones to leave the Merseyside outfit in the summer of 2015.
“Martinez was really fortunate to the get the job in the first place, on the basis of Wigan beating a very poor Man City side to win the FA Cup,” Keys wrote on Sport360.com. “I have never understood the fuss about Martinez.
“His decision not to sell Stones to Chelsea was disastrous. When a player wants to leave you must sell at the optimum point because he will never be the same again and that is exactly what has happened. Stones has gone backwards and they will never see an offer like Chelsea’s £40million ever again.”
Stones has created four chances in 29 Premier League appearances for Everton so far this season. The youngster has a pass accuracy of 89% and a shot accuracy of 14%, and has won 46 headers, 21 dribbles and 34 tackles.