Yeah that true but Sevilla would have been favorites to even try to replicate such kind of thing, when they were at their prime they actually played very well and won the Europa league for a good amount of times although they weren't back to back but it was very difficult to see Sevilla and not be scared during that period in the Europa league because even their league performance was poor it wasn't the same with their games in the Europa league.
However, next season Sevilla will not be in the European league, because they failed to get tickets to go there because of their poor performance last season which meant they were at the bottom of the standings.
Their record in the Europa League is actually quite good, where they are the team that has won the most titles in the Europa League. However, their performance is not very consistent, especially in the domestic league, which is a problem for them.
Now Sevilla must first focus on improving their performance and being able to compete in La Liga, so that next season they can be in European competition again. They are a good team, it's just that they have had problems in the last few seasons.