The Dutchman believes the England international is still an important figure at Old Trafford despite the club's reliance on Robin van Persie for goals in 2012-13
Goal exclusively revealed last month that the 27-year-old is determined to force a move away from the club and is adamant that he will not be able to work with incoming United boss David Moyes.
Van der Sar concedes Rooney's last campaign was subdued when compared with previous seasons but believes the forward still has an integral part to play at Old Trafford.
"It was maybe a lesser season and he didn't play the last couple of games but he's really important for United," Van der Sar told BBC Radio 5 Live's Sportsweek programme.
"English players tend to stay in England to play their football and rightly so because you have big clubs, the tradition and the stadiums are always full.
"With the change of manager and backroom staff it could be a big change for Manchester United but I don't think you'll find a better atmosphere at many other clubs."
The Dutchman believes the expectation placed on Rooney makes the striker an easy target for criticism but insists the England international should still receive acknowledgement for his contribution.
"There has been so much pressure on him, you build him up and put all your money on him to make England world or European champions," Van der Sar said.
"So it's also quite easy to cut him down again. Players have indifferent seasons and maybe Wayne's been overtaken by Robin van Persie this year but it's the hard work that he puts in for the team [which should be recognised]."