Actually, Sevilla's failure in the Champions League was predictable by looking at their performance in La Liga. In La Liga alone they have only recorded 2 wins from the 16 matches they have played, so I'm not too surprised when in the Champions League they didn't even win once.
Sevilla's decline is obvious, so it's not unusual for them not to be able to place at least in the Europa League this season. The managemen must totally evaluate the team, as they are also in danger of being relegated this season. They are 16th with 13 points, the same points that 18th-placed Cadiz have. That's certainly not good for a club that is known to be good in the Europa League, and they are even the club that has won the most titles there.
It's natural for what happened to Sevilla because their performance has not improved since the start of the season, I regret what happened because last season Sevilla's performance was not that impressive even though they won the Europa League and the team management should have been more serious in building the team but in fact they it didn't work until now.
Now the competition between European teams is really difficult to predict because some teams are starting to develop so rapidly that there is equality of quality which makes anything possible.