It proved wrong on every count, Balotelli providing the pass that made them champions for the first time in 44 years and rendered the post-mortem examinations on their challenge that followed April's defeat at Arsenal both premature and misjudged.
This time, however, the inquests can safely begin. Twelve points behind Manchester United with 12 games to go, the game is up for City. Now their immediate rivals are Chelsea and Tottenham Hotspur, not their neighbours.
Second place is far from a formality, particularly after Saturday's abject capitulation a Southampton.
And, in any analysis of where it went wrong for City, the Southampton game is a logical starting point.
Not the weekend's match, tamely as City surrendered, but their opening-day victory against the Saints.
Their campaign was seven minutes old when Sergio Aguero was hurt in a challenge with Nathaniel Clyne.
It set the tone for a stop-start season where rhythm and momentum has eluded City. It is a campaign that can be measured in medical bulletins, about Aguero's knee, David Silva's hamstring and Vincent Kompany's calf.
Before his departure, Balotelli contrived to be ill and injured at the same time.
Jack Rodwell and Micah Richards have hardly been seen, their comebacks postponed time and again. The Toure brothers, Kolo and Yaya, were other absentees, disappearing to Africa for a month. City's forgotten man Scott Sinclair stayed fit and available but just vanished.
If title challenges are built on individual contributions, then City were deserving winners last season. Aguero, Silva, Kompany, Richards, Yaya Toure and Joe Hart all had a terrific year.
Twelve months on, Pablo Zabaleta has been the lone beacon of excellence throughout the campaign and it is unlikely any City player will figure on the Footballer of the Year shortlist.
Instead, their successes have been unobtrusive. Gareth Barry was quietly dependable until his meltdown at Southampton, the unheralded James Milner has proved effective and the defence, after early-season problems, reasonably reliable but the principal shortfall has been in the attacking areas.
Mancini has regularly bemoaned a lack of goals. City had scored 19 more at this stage of last season.
They have gone from fast and fluent to more laboured. While Silva and Aguero have not proved as creative or as prolific respectively, others have not compensated. Frustration with Samir Nasri mounts by the game as his capacity to go missing when it matters most increases.
In contrast, Carlos Tevez is rarely anonymous but his incessant running has taken him up umpteen blind alleys.
Even with him in Argentina for much of last season, City had the Premier League's most feared group of strikers.
Now that mantle, like the title, is being transferred to United. The reality that the Manchester rivals were only divided by goal difference last season and then United signed the division's outstanding player.
The shift in the balance of power came the day Robin van Persie swapped Arsenal for Old Trafford; the moment the crown slipped from City's grasp came when the Dutchman's injury-time free kick, aided by Nasri's half-hearted defending, gave United victory at the Etihad Stadium in December.
That Mancini wanted Van Persie makes it doubly galling for the Italian; this was all too predictable for him. It is easy to be wise after the event but Mancini was outspoken last summer, voicing his belief that clubs should buy from a position of strength.
It is an argument that looks all the more compelling now. His A-list targets, Van Persie and Daniele de Rossi, eluded him.
Each would have been expensive and, in the second half of their careers, would have had a diminishing resale value. Yet while Financial Fair Play is rightly a concern for City, their recruits have largely been footballing failures.
Only Matija Nastasic of the five principal summer additions has succeeded. Javi Garcia is an inadequate replacement for the underrated Nigel de Jong. Maicon has been a bit-part player. Rodwell is invariably injured. Sinclair has only been trusted to play 43 minutes of Premier League football in four-and-a-half months.
Apart from the promising Serb, each has proved a false economy. The consequence is that City, who had hoped that after the frantic and costly trading to propel them forwards, would be able to evolve more organically with occasional, judicious additions to an elite squad may have to consider a clear-out of the unwanted and the underachievers.
But the exodus should not extend to Mancini. Despite his disappointing, and deteriorating, record in the Uefa Champions League, there are few better managers in world football and one of those, Pep Guardiola, has already committed himself to Bayern Munich.
With his tactical nous, the Italian has transformed draws into victories several times but some of a bold decision-maker's choices have backfired.
And, from the directors' box to the dugout, glaring errors have been made. From the goalkeeper Hart to goalscorers, high-class footballers have failed to find their optimum form.
With their spirited rally last season, City won the league title as a team. With a collective failure to hit the same heights, they have lost it together.
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