Welcome also to the new format that we will start to see in the upcoming season. Atalanta became the team that managed to become champions, and they were the last team to become champions in the old format. This new format that will be implemented also affects the teams that participate later, because usually we will see a play-off match between the relegated team in the Champions League and the team that is in second place in the Europa League, this season we will not see that anymore. Sevilla became the most successful team, but unfortunately this season they will not be part of the Europa League because they failed to get a ticket to go here last season in La Liga. Actually they are a team that is always awaited in the Europa League, because they have a different appearance when they are here. Indeed they can't play well in La Liga, but when they are in the Europa League they are like 2 different teams.
The same as UCL, Europa league will also have more teams now. There are 36 teams to play in Europa league and there will be no group stage anymore. Europa league will have league stage that each team will have 8 different opponents. There will be more matches, I think this will make every team to be busier than usual. The players of each team must have a way to deal with their fatigue and prevent the chance of injury. When they will also struggle with domestic competitions that become more competitive, I think Europa League matches look like be harder. I don't know why there should be a new format with more teams in both UCL and UEL, this never gives an advantage to every team.
Anyway, we won't see Atalanta in Europa league again. They will join UCL in this season, but I am not sure they will play well in UCL. They could win Europa league trophy because they could defeat Leverkusen last season, but in UCL there will be stronger team. If Atalanta could reach knock-out round in UCL, it is a great achievement for them.
Left alone with me, I would have preferred the old format. Maybe one of major reasons for this new format is to increase the number of clubs that participate in the European Leagues, and maybe give those clubs a sense of belonging as if, they are in the champions league.
Of course Europa League matches are harder because your meeting teams that are almost on equal strength with you, couple with the fact that European competitors comes with a different aura, so they should expect it to be tough.
Atalanta will certainly play well in the UCL, this was exactly how they were looked down upon until they won the Europa League for last season, the team has a lot of composure and tactical strength from what I've seen, and is certainly one of the clubs to look out for this coming champions League season.