It's been revealed that Koeman and De Boer have the same agent.
Don't know what the reaction to this will be, but former player Michael Ball rates De Boer:
http://www.liverpoolecho.co.uk/sport/football/football-news/everton-manager-search-frank-de-11325142
Michael Ball played alongside defender De Boer at Rangers in 2004 and believes the Dutchman would be "refreshing" for the Toffees.
"He likes to bring a lot of youth into his teams and, with the Everton squad being so young, it could only be a positive for him," said Ball.
"I know he's unproven in England, that's the only negative. I think De Boer would be refreshing for the Premier League and refreshing for Everton."
Everton need to start aiming for the best managers available,” Ball said.
“That is what we want to see now and though Jose Mourinho has been mentioned, but we don’t know if he’s got an agreement with another club or not.
“I may be biased, being an ex-team-mate of his, and he is unproven in England but Frank De Boer is a winner.
“He knows what you need to win. He will be demanding of the players.
“He likes bringing the kids through the system and he would be a massive influence on the club’s young players but also on the senior ones as well.
“He will make it clear how he wants them to play and he has a proven track record having won four of the last six league titles in Holland.
“He is someone the fans can have a connection with.”
“There is a lot of emphasis on trust in each other,” he said.
“He knows what it takes to win things and he wants good players to play the right way but if they are not doing the right things then he will be shouting them down, they won’t be getting away with it.”
Ball says he wasn’t surprised to learn of Martinez’s sacking earlier today but says he felt a decision should have been taken much earlier.
“I felt like it was a missed opportunity and that it could have been done earlier,” Ball said.
“After the thrashing at Liverpool, Everton were never going to go into the FA Cup semi-final and be on the top of their game.
“If he had gone after the derby then there would have been a reaction from the players and fans at Wembley
“I’m left thinking ‘what if’?”