David Moyes has said that Everton's successful season is "not a surprise" given the legacy Roberto Martínez inherited from him as manager, as the Scot prepares to take Manchester United to his former club for the first time.

United have struggled in Moyes's first season and stand seventh, nine points behind Martínez's team, going into Sunday's game. Yet he pointed to the squad he left and the firm foundations built while manager there for 11 years.

Asked if the opinion that Everton are more exciting under Martínez is fair, Moyes said: "They have some really good players and they have gone on again. Great credit to Roberto but he has a group of players who were always capable of going on again, of improving. Maybe moving further up the league. Don't forget Everton finished above Liverpool last year – and the year before. So it was a great achievement for Everton. In a way it should not be a surprise they are doing well.

"He's picked up a really good group of players, there's some top senior players there. There has always been a chain of young players ready to go in the team and I think that's helped. We had a great recruitment department, a brilliant staff, all round the club. All those people have helped. It's a well-run club."

Moyes has drawn animosity from some Everton fans for identifying Marouane Fellaini and Leighton Baines as targets for United. A section also believe Moyes knew before last May he would replace Sir Alex Ferguson as manager.

Yet the manager, who has not been back to Goodison Park since leaving the club, believes that most supporters have moved on. "I went to see Everton on Saturday against Sunderland [away]. I've not been back to Goodison," he said. "I've just felt that it wasn't the right time to go back at this moment. Time is big healer as well. It is nearly a year since I probably only found out about the opportunity [to join United], it was about May 1 – April 28th, something like that."

What needs healing? "Possibly the way people see me leaving," he said. "Maybe people don't believe how it happened. I think there was animosity because of the players – we'd like to have bought a couple of them. But lots of United players go to Everton – so there is a reverse."

Moyes, who has Wayne Rooney fit again following a foot problem, suggested that despite last summer's difficult transfer window and the club's intention to make signings before the World Cup, that may not happen.

"It's difficult as players are going to be going away for the World Cup so it's maybe not quite as easy as, ideally, all clubs would like to get the work done early," he said. "We cannot guarantee it but we will try to make that happen. I've got to say I'm well into my planning with my thoughts and ideas, getting ready for next year. Not everything you read is correct, I've got to say that.

"We're linked with player after player and every time I go to a game I'm supposed to be signing three or four players from that game. That isn't the case but everyone is well aware we are looking to make signings and will try to do that whenever the opportunity arises. It will probably be after the end of the season before anything takes place but we have got to look to do one or two things."

Next week United's medical team will visit Robin van Persie in the Netherlands, who has a knee injury, to analyse how he is recuperating. "Our medical team is heading out there to see him this week and get a better feel as to exactly where he is," Moyes said.