I agree that they were decent, but remember that we have seen Liverpool lose to Atalanta 3-0 when they were the leaders in the league, that should tell you how hard these competitions are. Of course they dropped to third place later on but that doesn't change the fact that we had them at the top during the time of the loss, a team leading premier league would be expected to beat most teams in the world, including UCL teams too, maybe not Real Madrid, but there aren't that many teams leader of premier league could lose to, and yet they lost to Atalanta.
So saying that United is good right now is true but also they could lose is once again true as well. Just because they look good, doesn't mean that they are going to win it, so much so that even if they end up being somehow incredible and win the premier league and shock the whole world, that still doesn't mean that they will win this one too. You have to play game by game to see how it will end up.
Liverpool's defeat in the Europa League against Atalanta last season was quite surprising, not only that because they also lost with a fairly big score at that time. So just like the others, the Europa League is also quite difficult to predict.
Talking about Manchester United, actually every season the squad they have never lacks good players, but for some reason the players can't show their best abilities.
I think this has something to do with the strategy that is applied, maybe it's not suitable for the Manchester United players so they can't show their best performance.
Although the Europa League is the second tier below the Champions League, but it does not mean that the top teams which play in the Europa League are easy to win. At least there have been many surprising results, and one of them also happened last season about Atalanta who was not the favorite team at all. But anyway, the fact is that Atalanta was able and managed to beat two favorite teams last season in the Europa League, and Atalanta also managed to win with a big score in the quarter-finals beating Liverpool and in the final defeating Bayer Leverkusen which both managed with a score of 3-0 as well.
Clearly, it was a surprise and also proof that in the Europa League it still won't be easy for the top teams to win the trophy. Moreover, the assessment of Manchester United at the beginning of this season is also not completely perfect, although they get three points there but the reality is that it is also not easy for Manchester United to get it. Therefore, of course we cannot say Manchester United will get the Europa League trophy this season, but about a chance at least they also have a chance but it is still not a guarantee of winning the trophy.