If Juventus improve their performance in defense their chance for the Europa League title will increase quite much as well. I mean that they are really solid in defense as for the Serie A. However they couldn't show the same level of performance in their Champions League matches. Their defensive weaknesses sped up the process for them to be eliminated.
However if they manage to perform in the Europa League at the same level of their performance in the Serie A then I will add them among the favourites. But for now bookmakers are showing Arsenal as the closest team to the title. Arsenal have cared about not only the Premier League but also the Europa League so far. With this discipline level they really have a big chance to make it.
Juventus are weak defensively which have been a major cause in their drastic drop in form and resulting in poor games in the league and in the Champions league. Their performance in the league have been much better than in the champions league which seems to me that to evaluate a teams performance, you will get the right answers when they compete in European top level like in the Champions league or Europa league because you are competing on a different level there against the best in Europe. That could probably be the reason why they play better in the domestic league and not in the Champions league. However, they need to strengthen their defense to stand a chance in the Europa league.
Juventus have been going through a lot of poor performances in the lead up to the World Cup. There were many injuries in the team which affected the team significantly. If Juventus want to do well, they need to return to good performances. However, I believe that whatever qualification players Juventus have, they will surely be able to return to performance.