The former Tottenham Hotspur and Reading attacker has scored just one goal and looks a fraction of the player that saw him almost single-handedly keep Swansea in the top tier of English football during the 2016-17 campaign.
Nevin claimed that the Iceland international needs a striker that he can link up with, but is confident that the Toffees' number 18 will become one of the club's best players eventually.
“I was one of those people, when they started talking about the money Everton were preparing to pay for Sigurdsson, who thought, ‘that is a deal I would take every day of the week’,” said Nevin.
“I watched him a great deal last year and, for me, he was one of the top six or seven players in the league. That is saying something, considering the amounts of money that have been spent.
“He does need somebody to find with his passes, but if you put him in any team in this division – and I mean any team – he would look perfectly at home. He just needs someone he can aim for, and whose movement he can understand and work with.
“In time, do not worry, he will be one of the Club’s top players… one of the players who is really loved at Everton.”
Last season, Sigurdsson scored a huge 10 goals from attacking midfield and provided the creative spark in Swansea's side with 13 assists, something he is yet to reproduce at Everton.
The Toffees currently sit in a lowly 16th place under interim boss David Unsworth, after climbing out of the relegation zone with an enthralling 3-2 win over Watford last time out.
It is clear that Everton miss the presence of Romelu Lukaku up front, who joined Manchester United in the summer. Sigurdsson is expected to feature in the Toffees' next outing, as they travel to Selhurst Park on Saturday to face Crystal Palace.