The Europa League is different again from the Champions League especially now with the new format I think it will be even tighter while we know Atalanta so far in Serie A are still bad they lost to Inter Milan badly and lost again to Torino.
Not underestimating Atalanta but the reality is it will be more difficult but I see the fixture with Arsenal will be more complicated than before with Leverkusen during the Europa League final.
So far there are no big expectations from Atalanta, considering some of the teams they sold of course the squad now will be different from before, but I want to see the action to see how far Atalanta go in the Champions League.
Usually teams that does better than expected gets their players either transferred out for a lot of money, or they use their new money to build a new squad as well, get better players and it takes time to adjust and get used to or even maybe fail.
Atalanta lost just one important player, but got many players and they are not looking good for the time being, maybe they will be great soon, or maybe they will be terrible, I do not know because these things take time but it's clear that we are not seeing the Atalanta from last season. They do have a chance to maybe go to next stage at UCL if they get any better, but I think Gasperini has a lot more things he needs to take care of this season compared to last season, he has to deal with more issues.