The Premier League champions finished with just three points from their six matches—becoming the first English team to compete in the group stage without winning a game.
City's hopes of reaching the Champions League last 16 were already gone, but victory in Germany would have offered the consolation of a place in the Europa League. Defeat meant that spot went to Dutch side Ajax instead.
On Matchday 6, Real Madrid did City a favor by swatting aside Ajax 4-1, but Mancini's team never looked like achieving the victory they needed against Dortmund to go through. In truth, the scoreline was kind to City, who were outplayed for the second time this season by the impressive German champions.
The postmortem into City's second successive European failure now begins in earnest. Having spent over £1 billion assembling one of the most star-studded squads on the planet, City's underwhelming campaign can only be read as underachievement.
Put simply, City deserved their fate in Group D. They were outplayed by Dortmund and Ajax across four games and failed to capitalize on two opportunities to beat Madrid.
Nobody can argue City were drawn in the toughest of eight groups—the much-fabled 'group of death' containing four domestic title winners—but the very least their fans could have expected was third place and a run in the Europa League.
Things started so well. City led twice at the Bernabeu, only for Cristiano Ronaldo to complete a rousing comeback and steal a 3-2 victory for Real Madrid. A 1-1 draw at home to Dortmund followed before City were ripped apart in a 3-1 loss at Ajax.
All hopes rested on a big win in the return game against the Dutch side, but a bold Ajax side came to the Etihad and deserved the 2-2 draw they went away with. City then effectively needed to beat both Madrid and Dortmund in their last two games, and that wasn't going to happen.
City's campaign ends with just three points from a possible 18 and many seriously doubting Mancini's aptitude for leading his team in their quest to win European club football's biggest prize.
The good news for City's manager is he has a Manchester derby at the weekend to answer back in. The bad news is that patience is not usually in generous supply when it comes to billionaire owners and their clubs failing to make a mark in the Champions League.