Aston Villas goals were quite perfect frankly speaking and Baily doesn't score that goal from that angle 100% of the time. Then the freekick and only that one lucky goal for Manchester United. That is what I think shouldn't happen. Manchester didn't fight back as a great team would do. They didn't get their organisation right and weren't sufficiently dangerous in Aston Villas box despite having amazing players in their offensive lines. Aston Villa was greatly prepared and they delivered a real fight. That's why in the end the three points were well deserved.
Manchester United have stability issues, especially when it comes to away games. At some point, when it seems that ten Hag was able to improve the game of the teams, they manage to get defeated by not the strongest team. But Emery's presence may have played a role here, now it will be interesting to see the results of Aston Villa, since Emery is a very good coach and can significantly improve the team.
I think on average most teams are weaker in away games, but for a team like Manchester United it shouldn't be the case that they concede over two goals per game on average in away games, which is the situation right now. There defense in away games is among the worst of the whole Premier League...
It is quite common that new coaches bring some new impulses into the team, but often times that is more of a psychological thing than real changes in strategy and ability. That is also an important aspect of course as it helps building confidence in an otherwise discouraged and insecure team, but what also often happens is that this first effect falls flat after a while. From what I saw in the game there is definitely potential though and some serious quality.