I think Sevilla is a completely different case, because they are really very good inside the Europa League, they are confident here and they are not afraid of anyone, no matter what opponent is waiting for them. I don't know how this can be explained, but their performances inside their league look a bit worse than inside the Europa League. However, they are not in the Eurocup this season, let's see if they can perform next season
Sevilla is not a different case. They have had bad performance in the Europa League, but they got away with it. When they played this game against Manchester United I think in the quarterfinals, Manchester United scored two own goals in 84' and 90+2'. Do you know how often that happens in football that a team scores two own goals in the last 8 minutes of the game? That was a huge bummer for Manchester United and it turned the whole match upside down. If Manchester United had a two goal advantage in the second game, the game would have been fundamentally different.
But that is how it goes and it is these incalculable things that decide over success and defeat. It wasn't because Sevilla played better in Manchester. However, they did play much better in Sevilla. So nobody knows how that would have ended anyway.