Wilkinson, who has twice toured with the Lions and won five Test caps for Britain and Ireland's elite, has come under fire from critics for his form in an England shirt.
The former Newcastle and Toulon fly-half has often being singled out for praise but he is now being highlighted as a weak link in the current England set up.
But Cohen, who toured Australia with Wilkinson and the Lions in 2001, believes Jonny is still the quality player he was when England won the World Cup seven years ago.
The difference, according to Cohen, is the status of the players around him.
In 2003, Wilkinson was surrounded by hugely experienced English Lions who all had key roles to play. In 2010, Cohen believes Wilkinson is required to shoulder far more responsibility on his own.
"England aren't the team they were," Cohen told PA Sport.
"You had the likes of (Lawrence) Dallaglio, Matt Dawson, Will Greenwood - they are people in the side who were fantastic at making decisions and were leaders.
"It made Jonny's life a hell of a lot easier, especially with Dawson inside him and Greenwood outside him. It made my life a lot easier.
"Will Greenwood was generally the guy who ran the back-line. He was a key figure, along with a lot of other players in that team. Jason Robinson would tear it up and we would try and play off that.
"Will would always score tries and he was the brains behind the side. It doesn't mean that Jonny wasn't, but he had a lot of help and I think probably that is what is lacking - the people around him."
It wasn't long ago that a fit-again Wilkinson was being hailed as England's saviour and Cohen insists his former colleague hasn't become a bad player overnight.
The Sale wing, who won 57 caps for his country, says Wilkinson is still one of the hardest working people in the game, and no different from the player that helped England become the first Northern Hemisphere side to be crowned the globe's greatest in 2003.
"Jonny is a fantastic player and a fantastic guy, but he hasn't really changed that much in his game from when we played for England early on and when we were involved in winning the World Cup," added Cohen.
"I'm not saying he is a bad player, but he hasn't changed. People are saying he is a bad player now - okay, he could play a bit flatter to the line, but he is still a great player who puts in a lot of hard work off the pitch and plays to 100%.
"It's just how people see things now and it just makes me laugh that everyone can attack one person."