Roberto Martinez says Everton defender John Stones has grown as a person as a result of interest from Premier League champions Chelsea.
The 21-year-old England international was the subject of a number of rejected bids from Chelsea during the close-season transfer window as Everton held onto one of their most prized assets.
Stones continues to be linked with a move away from Goodison Park - fresh rumours in recent days suggesting interest from Barcelona - but Martinez feels the centre-back is now better equipped to deal with speculation over his future.
"One hundred per cent, everything that went on in the summer helped John grow as a person and a player," the Everton boss told reporters.
"You need to understand the human side of a footballer gets heavily tested in a period like that. You get a lot of influences and some influences were wrong from the outside and they affect you.
"We have seen in many dressing rooms how players get affected and disturbed. I think that John from day one had a really good supportive group of people, especially the players in the dressing room and everyone at the football club to help him.
"It has been a very important period for his development. Psychologically he has become a man in a very short period of time and a footballer who knows how to cope with high-pressure situations and be able to perform on the pitch.
"He is an important player, he is our number five and to be number five at a club like Everton is quite significant at such a young age.
"And it's not just the way he is developing as a defender, but the way he is developing as a leader. He's someone who can affect the players around him."
Stones' contract at Goodison expires in 2019, having become an established part of Martinez's side since arriving from Barnsley in January 2013.
On the defender's long-term future, Martinez added: "We have a really good relationship with John's people because they have got another six players in the first-team squad. It's not an issue.
"He is still on a long-term contract and nothing has changed. Any player who performs well in the first team, we are a football club that wants to reward that good work on the pitch and that will never change."