England have slumped down the rankings since their 2003 triumph with coach Andy Robinson recently paying the price for the team's failings. They have lost 18 of their last 30 Test matches.
Johnson, the man who lifted the World Cup three years ago, attributes the decline to the high number of games being played for club and country.
"What the players were asked to do from the start of the World Cup campaign in 2002 through to the 2005 Lions tour was just ridiculous," Johnson said.
"If I had not retired when I did I'd either have spent the past three years injured or suffered from a drastic loss of form, which is pretty much what happened to the majority of the World Cup squad. Everybody hit the wall."