The Merseyside outfit are yet to keep a clean sheet after three Premier League games, with six goals being conceded in last month's defeat to Chelsea at Goodison Park.
"It has been a surprise because we have not lost any players in that back five, they have incredible experience with over 1,100 Premier League games between them," Martinez said in this morning's press conference.
"It has been one of those situations where everything that could go wrong in our box, has gone wrong. We are aware of what we have to improve, but the margins are very small. It is not about a need for drastic change or revolution."
The Toffees are currently 17th in the league table.