For example Arsenal, they will also be very busy maintaining their position in the Premier League. Manchester United are busy trying to get into the top 4. Juventus are busy trying to stay in the top 4 and all the teams competing in the Europa League have other competitions that are just as busy. So it's not only about Barcelona.
you are right The teams competing for the title in the Europa League this season are all looking to do well in their respective leagues. Barcelona and Arsenal are aiming for the league title. On the other hand, Juventus and Manchester United continue to fight for Champions League qualification. So the Europa League is probably the second priority for all the teams. And so it cannot be said for sure how the teams will perform in the Europa League.
Some of them were big clubs that have bad performance during last season and the rest were clubs coming from champion league caused by they would not able to pass into the last 16. Im still feeling doubt about the performance from those big team.
They were at the europa league caused by they were not able competing with the team that were currently battling in the champion league. I see this competition is only a training for the one who will be qualified for champion league for next season.