Per the Guardian:
Manchester United have joined Manchester City in the race to sign Robin van Persie.
Van Persie is a fantastic player and a goal scorer of the highest caliber, but United don't need to spend £20 million or more on a striker when there are other positions of weakness that must be addressed.
The Red Devils scored 89 goals last season (which ranked 2nd in the EPL) and are fortunate to have a world-class forward in Wayne Rooney and a young striker in Danny Welbeck who is quickly becoming one of England's best attacking talents.
Ferguson needs to strengthen the back four and not add another expensive goalscorer. Left and right back are a concern for United, and depth at center back is also an issue.
Neither of these two players would be as expensive as van Persie, and they would also be signings for the future. The Arsenal captain is already 28 years old.
Adding van Persie would be a quality addition to United, but his age and price tag should make Ferguson look in another direction during the summer transfer window.