The main reason people think Sevilla is a strong team is they just see the results they get and they don't pay attention to the situation of the games they have,
People think that if how many trophies being collected by the team will always represent how strong that team is. I do know if sometime this can't be used as a benchmark but im thinking about this is still making sense to call the team was strong.
That proves how consistent the club in winning the competition, right? The fact that if sevilla is strong enough right now consider it has beaten so many candidates from another club.
I would not be surprised to see some people counted how many UEL trophies have been colected by sevilla as a thing that was also affecting the performance from the club.
for example, we know against Manchester United they had no chance and the reason why they won the game was just because of the personal mistakes in Manchester United defenders, otherwise, Sevilla could easily lose that games against Manchester United.
I do agree with this but it must be noted if sevilla won't use all of golden chances properly and i think that sevilla won't able to make a lot of scores against manchester united.
There are some things that contributed a lot to the lose of manchester united against sevilla. These things are
Personal mistake
Proper finishing
Stability of team
Sevilla has it all.