Toffees ace improved from Chelsea transfer saga.
Class! Arsene Wenger announces Arsenal will donate to Syrian refugees
Chelsea transfer news: Blues set sights on £71m duo for January, including Arsenal & Man Utd targets
Fastest players on FIFA 16: Arsenal star Theo Walcott ahead of Chelsea & Real Madrid speedsters
The England international was long linked with a big move to Stamford Bridge, but ended up staying with the Toffees after Martinez rejected several offers from the Blues.
Stones handed in a transfer request, but his manager is not concerned by the effect of this saga on his performances, according to the Daily Express.
“He has been performing on a very, very good level,” the Spanish tactician said.
“John has gone from strength to strength in a period of high pressure. He has taken the support of everyone and you have seen him perform for England in a very natural manner.
“That is a sign of the calibre of the player.”