Ferguson has described the fuss over a potential confrontation with the Manchester United striker over their different assessments of an ankle injury as "water off a duck's back".
But while Redknapp agreed Rooney had been off his best in recent months, he backed the England star to return to his prolific goalscoring form of last season if United support him.
Redknapp said: "Rooney will come back stronger than ever. We'll all look back on it in a year's time.
"Everyone goes through dickey spells in their career and he's just having one of those spells where he is not playing as well as he can. A year ago, he was as good as anybody in the world.
"At any given time, he'll go out and get two fantastic goals, win the game for you.
"When you have got an amazing talent, it is difficult to leave him out. You're not going to play him in the reserves. You've just got to let him play his way out of it when he's so good."