Regardless of everything that actually happened, these two clubs have actually improved compared to before, but there are indeed some criticisms and doubts about their internal problems, such as Manchester United with all kinds of problems with its players and Xavi who is still criticized for losing 2 times in a row in 2 seasons in the Champions League which made him seem powerless for big competitions.
On the other hand it will be a good play-off because the one who wins from this game will be a candidate who is actually quite strong in the europa league.
They are both big clubs and have many star players in their squads. It is enough to create exciting matches between them in Europa League. Their latest forms before their meeting can make us feel one team are stronger than another. However, on field their player performances will decide and some times, surprising bad or good performances can occur which are totally different than their latest forms.
Manchester United's chances of getting the Europa League trophy this season are open, it's just that the opponent they will face now is Barcelona, which we know is one of the tough teams and also the favorites to win the title in the Europa League this season. That is their toughest challenge in this play-off round. Also if they are able to get through this play-off round perfectly, the hurdles are still in front of them, because some of the big teams are also here after failing to qualify from the Champions League.
Manchester United belong to biggest teams in Europa League this season. With their squad, player quality and latest impressive form in Premier League, it is reasonable to put Manchester United to best candidates.
Being one of best candidates won't bring Europa League trophy to Old Trafford. They must beat so many big clubs and Barcelona will be their first challenge for the dream. I consider Manchester United and Barcelona are very balancing and it's hard to choose what team are stronger.