Known for his charitable work, and reportedly willing to play for free, United threw Hargreaves to the wayside, presumably believing that injuries had finally overwhelmed the once great player.
A two time Champions League winner, Hargreaves is about as cosmopolitan as an Englishman can be - fluent in German and an expert penalty taker. During his time at Bayern Munich, he gained legitimate respect from more broadly versed European football observers, his talents appreciated as being many varied and translatable to more than just the parochial atmosphere of English football.
At the 2006 World Cup, a series of dynamic performances - culminating in a penalty conversion against Portugal - earned Hargreaves the attention of Sir Alex Ferguson and, eventually, a move to Manchester United in the summer of 2007.
"It has been a long time coming - it was probably the worst kept secret in football." said Hargreaves after sealing the switch. Certainly, no similar claim could be made about his move to City.
So dire was Hargreaves' situation, that he was forced to post fitness videos on YouTube to convince potential suitors of his worth. Clearly, Roy Hodgson and West Bromich Albion were impressed by his ability to weave in and out of cones, as it was they who registered a first major interest.
"We believe he is capable of playing top flight football and we are very interested in him," said Hodgson. Having passed a "minor medical" at the Hawthornes, a move to the midlands seemed a certainty only for football's transfer juggernauts to once again steal the show.
Rumors breaking Tuesday were confirmed by images of Hargreaves apparently undergoing a three hour medical at Manchester City's Carrington training ground, with a view to a move before the transfer deadline. For Manchester United, the story echoes of Carlos Tevez.
The last player to breach the divide, Tevez was also cast away having failed to earn the full trust of Ferguson. United were frankly lucky that Tevez's role as City's star striker never effected their own fortunes particularly greatly, but what it did do was change the perception of Fergie's "noisy neighbors." From Chelsea wannabees to Champions League contenders, City's meteoric rise will eventually see United unseated.
The part Tevez played in the drama should not be undervalued, even if his ties with both clubs are becoming increasingly strained. His is the story of a player who left Old Trafford and excelled, contradicting Ferguson's oft stated rule in most ironic style.
Now that the Mancunian battle is becoming a title tussle as well as grudge match, United cannot afford to see their rejects perform across town. In Owen Hargreaves, City have found just the player they need, a much, much richer man's Gareth Barry - the midfielder who might have made two Champions League finals interesting.
Grasping for motivation to succeed, Hargreaves like Tevez will not have to look far. The nature of his departure from Old Trafford - complete with patronizing good luck wishes and dismissive shrugs from impatient fans - should be enough to get blood flowing.
The challenge is immense, but the prospect of success will keep Hargreaves going. After three years of turmoil, the end is in sight; the reward for lonely hours in the gym, and countless slices by the surgeon's knife.
United though, must pray that their midfield crock doesn't turn into City's final jigsaw piece.