We have seen consistent good performances from Manchester united in the last few matches of the Europa league. Despite not doing well in the Premier league , Manchester united have played quite well on the Europa league platform. However , the problem has been that Manchester United's opponents have been relatively weak. I am waiting to see if United's players can play well against strong teams. If United can dominate and win against Real sociedad, I would say that Manchester United are worthy contenders for the Europa league title this year.
The closer to the final, the stronger the team they will face, that is a certainty, because other teams will try harder to win the title in the European League. Yes, Manchester United's performance in the European League is not as bad as their performance in the English League, but as you said, the opponents they faced in the first phase were relatively weak so it was more profitable for them to be able to get points. It will certainly be something different when we enter the knockout stages, they must be ready for stronger opponents.
Same doubt I had when Manchester United got defeated against Fulham in the FA Cup is what I feel against Real Sociedad, Manchester United might have had a good run in this tournament but they're currently very weak due to injury crisis and poor performance by some players they even suffered another injury by a defender meaning that they're lacking good options in that area and could like play some players out of their position when they meet Real Sociedad, Sociedad on the other hand got heavily defeated by Barcelona, maybe it could weaken them when they meet Manchester United or maybe they could use that as a challenge but either ways I don't trust some of this current players Manchester United have in their squad.