A need for leaders
There are better teams in Europe than Atletico Madrid, but there's probably no better team at protecting a lead than Diego Simeone's snarling, sneaky rottweilers. The second half was barely a couple of minutes old when the first signs of frustration poured down from the Old Trafford stands and the Manchester United players quickly lost their heads as well.
This was Atletico in a microcosm. They didn't look like scoring again after Renan Lodi's goal, but they didn't need to and they knew that was the scenario.
They turned the second half into an almost unwatchable mess of a game, players going down at the first sign of contact, needing treatment and killing the game. United simply couldn't build any momentum.
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But this was an occasion when you need cool heads and leadership and right now United are lacking in that department. Harry Maguire needs the armband removing for the good of his own game and beyond that there are too many hotheads in this squad.
Bruno Fernandes is a fantastic player, but keeping calm isn't one of his strengths. He player with anger during the second half and that doesn't help his game.
This was a time when United needed someone to calm them down, but instead they fell straight into Simeone's trap. They were angered by Atletico's opening goal, even though it never looked to be a foul on Anthony Elanga in the build-up, and struggled to control their emotions after that.
Referee Slavko Vincic produced a performance that suggested he was out of his depth, but by becoming frustrated United lost sight of their own gameplan and struggled to sustain any pressure on the Atletico goal in the second half.
A new nadir
United have had some pretty rotten seasons since Sir Alex Ferguson retired but after this early exit from Europe this could yet be the worst of the lot. That might not be reflected in league position - and if United somehow salvage fourth it won't be the case - but considering the money spent and the quality of players available, this has been a dispiriting campaign.
It began with dreams of a title challenge but has spiralled out of control to the point where United now look unlikely to even be back in the Champions League next season. The season review DVD should be titled If It Could Go Wrong, It Did Go Wrong.
United were fortunate to enter this second leg on level terms but still couldn't take advantage of an Atletico Madrid side who are having an equally disappointing season on the domestic front. The exit from Europe confirms what we already knew really. This will be a fifth successive season without a trophy for the club.
After nine years supporters are sick of hearing of the need for rebuilds but this season has probably confirmed that this is a squad again in need of new direction and new faces. A timid defeat to Atletico was a fitting end to their hopes of silverware.
Wing-back woes
Tottenham's wing-backs caused United plenty of problems on Saturday, to the point Matt Doherty and Sergio Reguilon were unfortunate to be on the losing side, and while Atletico's duo weren't as constant a presence on the game they were still a threat at times.
Spurs had success due to the presence inside of Son-Heung Min and Dejan Kulusevki, but Atletico didn't have the same third man runs so United were more comfortable, but there were still moments when the width held by Marcos Llorente and Lodi stretched the play.
Llorente shouldn't have strayed offside when teeing up Joao Felix and the issues of who was supposed to be picking them up because a costly one when Lodi headed Atletico in front from Antoine Griezmann's cross. Diogo Dalot wasn't tight enough to Lodi but he did have a couple of players around him at the back post and he probably needed to call for help before it proved to be too late.
Fred's influence
Fred's flicked assist for Cristiano Ronaldo on Saturday was his fourth in 15 games for United under Rangnick and having had the more creative side of his game unlocked recently he's now starting to play like a Brazilian.
He produced one backheeled pass to Scott McTominay midway inside his own half in the early stages, taking a couple of Atletico's midfielders out of the game. Then came a brilliant piece of ingenuity on the byline in the Atletico area, rolling past a defender to find space, a move reminiscent of Fernando Redondo for Real Madrid when he created a goal for Ronaldo here almost 20 years ago.
Fred was once again playing slightly in advance of McTominay and not only does that get more out of him in terms of his pressing, but he is starting to show some attributes to his game that had laid dormant for most of his United career.
Atmosphere
This was the first Champions League knockout fixture in front of fans at Old Trafford for three years, since the quarter-final first-leg defeat to Barcelona under Ole Gunnar Solskjaer, and a supporter base used to grand occasions such as this were determined to make up for lost time.
Rangnick had left a message to those in the Red Army signing section thanking them for their support and urging them to keep the volume high all night and it was a ferocious atmosphere in the early stages, with the visiting Atleti fans playing their part in that.
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The atmosphere shifted to one of frustration in the second half, with Atletico's game management antics and some of the decisions from referee Vincic.
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