I am not sure where should I place Manchester United this season. It is impressive to see them fluctuating like waves with such amount of defeats and unstable performance in English Premier League then they did well so far in UEFA Europa League. I can't trust them anymore. Athletic Bilbao is a solid team and if Manchester United played as they did against Wolverhampton or Newcastle United then they will leave from the first leg.
Tottenham Hotspur is another version of Manchester United but facing easier opponent, so better chance of playing the final game. That's all.
Compared to United, Athletic look like a top club - Athletic have 5 defeats and 26 goals conceded, while United have 15 defeats and 46 goals conceded

In general, 15 defeats sounds shocking.
If you look at it on paper, then Athletic or Bodo should win the Europa League, the rest of the results will be extremely unfair in terms of sporting logic.