Every team can be very superior, as you call it, when you go for statistical cherry picking. Aston Villa is a good team and they can beat a lot of other teams as could be noticed against Bayern Munich. They defend for a very long time and then they hit the opponent in the right moment when a mistake is made. Aston Villa is no joke, they can compete with the best. But they might not be able to do this for 38 games in the Premier League.
After the game against Bayern Munich, i had to do some statistical check on Aston villa and i found out they have been of good performance this season in their domestic league and even last season they weren't in a completely bad form so cumulatively its very possible they are an equal match with their opponent and not that they were weak as compared to their opponent its just that people had very higher expectation from their opponent because of the results they have been producing since this season in their domestic and other leagues. if they can survive so well in the very competitive premier league then most likely they shouldn't be seen as a weak side as they are indeed no joke.
The capacity of football teams differs, as also their mentality differ. Their strengths also differ and such affects their results. When you come to a team like Manchester City, the team is mostly delivering by their coach as the source of their inspiration. When you talk about a team like Real Madrid, it is the team bond and motivation of the individual star players that gives them hope coupled with their matured and experience coach. In terms of Aston Villa I can say that their biggest motivation is their coach who came in and change the narrative of the club. Manchester United which happened to be the team that will face Aston Villa is totally out of motivation. Their only motivating factor would have been a threat from the management against the coach, but since the management is in agreement with their coach there is no motivation whatsoever. I am not expecting a different result on Sunday from what they used to have.