Mancini's likely final act was being woefully outmanaged by Roberto Martinez.
Ben Watson's header was the dagger that killed Manchester City's FA Cup run. But the truth is that City had rolled over and died long before Watson's header pierced the twine behind Joe Hart.
Roberto Mancini had pooh-poohed the importance of the FA Cup in the days leading up to this final with relegation-threatened Wigan Athletic. but only a fool would have believed that this match did not hold the manager's tenure in the balance.
Pundits had talked about how the FA Cup was a cold comfort for a disappointing season at the Etihad. But a cold comfort is surely better than none at all.
If you had any doubt as to whether City valued the FA Cup, you needed to look no further than City's team sheet.
Less than 24 hours before the FA Cup final, there was the Daily Mail prattling on about how Costel Pantilimon, who had led City to Wembley, would man the post for City in their quest for silver.
Except, not so much. It was Joe Hart between the sticks for City. Maybe Mancini's bluster about how his job should be safe was just idle talk after all.
Mancini certainly did not choose his XI like a manager unconcerned with the outcome.
Look at that side. That was Mancini's level best, the 11 players who had in the main brought him the Premier League crown last season.
The 11 players who he thought he could trust to grind out a victory against a Wigan side that more likely than not will be playing in the Championship next season.
Mancini put his trust in "his guys," only to see his guys repay his faith with a weak, tepid, sad effort.
There is no conceivable justification for this Manchester City team to have essentially equal possesion and shots as a Wigan team that was put out on the pitch for a pathetic fraction of what City's players cost.
That City ended the match with 10 men and that they conceded a last-minute match winner are only ancillary issues in the aftermath of this embarrassing, incriminating defeat.
A neutral observer would look at these two sides and presuppose that City would be up 1-0 or 2-0 at the halftime interval.
But that same neutral observer would note that Wigan had one, perhaps two, legitimate cries for penalty in the first half. The Latics wanted the FA Cup more than City's mercenaries from the opening touch to the final whistle.
Until this point, my rhetoric has been that Roberto Mancini deserves the opportunity to take an improved City side into Champions League play next season.
That is a very hard argument to make now. If Mancini cannot inspire this opulently assembled squad to beat a ragtag Wigan bunch, what can he be expected to do against Bayern Munich or Borussia Dortmund?
More of the same, probably.
Whatever Manuel Pelligrini might bring to the Etihad, it just cannot be worse than what Mancini produced with a defending Premier League champion this season. Can it?
What could be worse than bombing out of the Champions League, losing the Premier League title in April, then losing the FA Cup to freaking Wigan?
City paid filet mignon prices for skirt steak.
For Roberto Mancini, perhaps it is time to say goodbye.