The Scot retired at the end of the 2012-13 season after guiding the Red Devils to a 20th Premier League title, with David Moyes appointed as his successor.
A dismal campaign resulted in Moyes being sacked back in April, before Louis van Gaal was appointed as the Red Devils’ new manager this summer.
If you look at the names they have, they will be a force in the Premier League
But United are still without a win under the Dutchman after Saturday’s goalless draw at newly-promoted Burnley.
Some have claimed that Ferguson did not leave the Red Devils with a squad capable of challenging for trophies.
But Arsenal boss Wenger insists that United’s decline cannot be blamed on his former foe.
“If things have not gone well at the start, it is not Ferguson’s fault,” Wenger is quoted as saying in the Daily Mirror.
“The world is competitive and it is a bit cyclical. Once you leave a club, you hope it goes as well as possible. That is what Ferguson wanted as well. Manchester United have just started the season and it will come back.
“If you look at the names they have, they will be a force in the Premier League. But I don’t worry too much about them. They made us suffer enough in the past!”
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news