The Old Trafford side's five league defeats each exposed weakness and need for investment in midfield
Manchester United's soft centre is there for all to see
Few things give football fans greater pleasure than revelling in the misfortunes of others. And, over the years, the Swansea City supporters have had few opportunities to gloat at their Manchester United counterparts.
So Sunday's chorus from the visiting Welsh at Old Trafford was particularly loud. "Eight points and you messed it up," they sang (or almost: the verb has been substituted in the interests of decorum).
As the Old Trafford faithful did not need reminding, eight points was the size of their lead over Manchester City a month ago.
It disappeared in the space of four games: defeats to Wigan Athletic and City and a draw against Everton when United led 4-2 with eight minutes remaining.
Should City beat QPR on Sunday and take United's crown as champions, the end-of-season inquest may focus on their April mishaps.
There is much to regret: a strangely subdued showing against Wigan which, in the absence of the rested Paul Scholes, reiterated the importance of a 37 year old who languished in retirement four months ago; the uncharacteristic carelessness as they let a lead slip against Everton; the safety-first approach that backfired at the Etihad Stadium, when it appeared United never considered actually attempting to win the game.
There are choices Sir Alex Ferguson may bemoan privately.
Javier Hernandez, who has lost his form at the business end of the season, was preferred to Danny Welbeck at Wigan.
Evidence of Rafael da Silva's defensive deficiencies were apparent - and indeed exposed by Athletic Bilbao in the Europa League - long before Everton arrived at Old Trafford.
The Brazilian right-back was at least partly culpable for three of the visitors' goals on a day when either of the sturdier pair of Phil Jones and Chris Smalling would have been preferable.
The omission of Antonio Valencia, Wayne Rooney's most reliable supplier and the division's in-form right winger this season, against City may have been inspired by Nani's previous excellence against Gael Clichy but history did not repeat itself.
Yet if one managerial mistake stands out, it was Ferguson's decision to ask Park Ji-sung to mark Yaya Toure last Monday in the Manchester derby.
Once again, it was a move plucked from the past, Ferguson imagining his big-game player, as the South Korean long was, still had the formidable stamina that enabled him to selflessly stop greater talents.
The Park of 2012, however, was struggling to keep up with the Ivorian distance runner even before Vincent Kompany put City ahead and rendered his presence on the pitch irrelevant.
Yet Park's problems were a microcosm of wider difficulties.
Others who might have lent energy to the midfield could not; Jones was needed in defence because of Rafael's failings, Anderson is sidelined and Darren Fletcher, long the man for the major occasion, has not played since November due to illness.
While Toure has been electric for City, United have suffered a power cut in the middle of the park.
Examine their five league defeats and there is a theme, one United would be unwise to ignore when the transfer market reopens.
Two came against Toure's City while a third featured another all-action African, Cheik Tiote, who turned in a monstrous performance when United lost at Newcastle in January. Both have an athleticism United lack in the centre of midfield.
Toure is taking up a status as their scourge.
The scorer of the league leaders' two goals in Sunday's win at Newcastle and the FA Cup semi-final winner against United last season, he may be the major difference between the Mancunian rivals. He is high class and high cost.
It is telling that, in the era of 'Glazernomics' - the limited spending at Old Trafford while the owners siphon off funds to repay the debts they incurred by buying the club - United have not invested in a Toure, a Sergio Aguero or a David Silva at the peak of their powers.
So Ferguson's job is harder. He is left with one superstar, Rooney, while he mixes and matches from a large supporting cast.
Despite recent misadventures, it is something he usually does adroitly.
And while there is an understandable focus on the setbacks that are freshest in the memory, the most complacent and calamitous choice came on Ferguson's 70th birthday when Park and Rafael were paired in the middle of midfield as Blackburn Rovers won 3-2 at Old Trafford.
While Gary Neville, the former United right-back turned pundit, has said it is the manager's worst nightmare to lose the title on goal difference, they ought to lament that December day.
In any case, United's goal difference of 55 is excellent, even if City's is eight better.
And, in the final reckoning, that may provide an accurate summary of the situation.
It is not a case of United slumping, but City succeeding.
If Ferguson's men beat Sunderland on Sunday, they will have 89 points, enough to win the league any other season, so criticism should be limited.
When City have a stronger starting 11 and Roberto Mancini has had greater funds to spend, when United have suffered more from injuries, particularly Nemanja Vidic's season-ending cruciate ligament problem, when they have lost both derbies, the surprise should not be that the title was lost but that they came so close to retaining it.
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