I always doubted that Barcelona would be able to reach the final. For two reasons: first, this competition is not at the level of this great club, it is difficult to motivate the team to compete in this competition. Second, this season was very bad for Barcelona, perhaps the worst season they've had in the last 15 years, so any better prepared opponent had a chance of winning.
Normally i would agree and say that a big and team like Barcelona is not really that motivated to really give their all in a competition like the UEFA Europa League, i mean in the end it is and will always be just the B-tier competition in comparison to the Champions League. That being said i really think that this year it was different for Barca because of the circumstances. I read interviews with Barca officials after they were eliminated from the Champions League in the group stage, that they really want to Europa League now because there you can also ear a good amount of money and Barca has 1,3 Billion € of debts. I read that Eintracht Frankfurt has earned around 60 Million € with the win of the Europa League. Barca would have also really needed that money.
Yes, I also have to disagree that Barcelona was not motivated enough to win the Europa League because they can use any amount of money that they can get their hands on right now. It is obviously not the standards of Barcelona but right now the problem is they have lowered their standards themselves. And if they want to do well in the next season they would have eventually had to buy new players and the money that they could have earned winning the Europa League would have certainly helped them.