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.
I am really feeling wired about your this statement about Juventus defence because recently after exit from Champions League they are at their best and in last five matches they concede no goal which is showing how things are working for them and right now they are third in Serie A table with before break they have best form so most chances they could be done good after this break even right now Napoli and AC Milan are also at their best, but both will feel pressure in Serie A and for the match in Europa League they are going to face Nantes which is having poor time in French League and can't compete with Juventus which mean their progress for next round is ok and after this we have to wait for the next announcement.