This is the second time that United have been relegated to the UEFA Europa League from the Champions League under Ole Gunnar Solskjaer, and it highlighted the dents in his United set-up.
United only needed a draw to progress through to the next round, but from the start, United did not seem at it.
The United lineup was immediately questionable, lining up with five at the back and with two holding midfielders, with the only sense or creativity hinging on Bruno Fernandes, Marcus Rashford and Mason Greenwood's shoulders.
It came as an even bigger surprise when United conceded two goals very early on, despite having such a defensive lineup, with Angelino exposing Aaron Wan-Bissaka on numerous occasions.
However, Ole did not change the team immediately, and United kept on getting dominated for much of the first half.
In the second half, to be fair to Solskjaer, he did revert back to a back four, bringing on the very talented Donny van de Beek, who should have started, for Alex Telles.
Due to this change, United did start to dominate the game more and more, but after missing plenty of chances, they failed to defend properly, leading to RB Leipzig grabbing a third goal after some disastrous defending from Harry Maguire and horrible goalkeeping from David de Gea, with the two seemingly stuck in two different worlds as Justin Kluivert seemingly put the game to bed.
Interestingly, right before the goal, Solskjaer resorted to bringing on Paul Pogba, who along with his agent Mino Raiola, dominated the headlines for saying that the Frenchman wants to leave the club.
Solskjaer also made another very curious substitution, by bringing on Brandon Williams for Luke Shaw, with this being the third player to play at left-back for United throughout the game, and therefore, Solskjaer seemed to waste a substitution at a very critical point in the game.
It made for dire watching as Solskjaer opted to bring on two defenders as United were 3-0 down, choosing to bring on Axel Tuanzebe and Timothy Fosu-Mensah for Aaron Wan-Bissaka and Victor Lindelof, instead of the very experienced Juan Mata and Odion Ighalo, or the pacey Daniel James.
Somehow, through some Pogba magic and some luck from set-pieces, United got two goals back after Fernandes scored a penalty and Pogba headed the ball onto Maguire's back in a corner, yet it was not enough to get them the draw they needed.
Whilst Julian Nagelsmann deserves his applause for the way that he set his side up tactically, he was helped significantly by his counterpart's ineptness, starting the game off with a draw as the objective against a very good attacking side.
Yes United had some crucial players out injured in Edinson Cavani and Anthony Martial, but the players available to Solskjaer were more than enough to do the job against RB Leipzig, especially with the likes of van de Beek and Mata not starting, with the two capable of easily changing the style of play.
United were left with a side that followed no particular system, and it highlighted Solskjaer's cracks in management, depending on individual brilliance for far too long, particularly from Fernandes.
However, the Champions League exit was not all down to Tuesday night, as Solskjaer had plenty of chances to get United through to the Round of 16, but once again showed a lack of know-how, mainly with the reckless defending away at Istanbul Basaksehir, and by keeping Fred on the pitch against PSG.
The comments made by Raiola did not help at all, especially before two very crucial games against RB Leipzig and the Manchester Derby in the weekend, bringing a negative energy to the team.
Whatever the case, Solskjaer was outclassed by Nagelsmann on all managerial areas, and some very strange substitutions and tactical decisions has led to United playing in the Europa League once again.