Nobody thought of Atalanta in the beginning of the league because we believe more in big clubs. Liverpool was doing perfectly OK in EPL, and Leverkusen was winning their matches and this was what made most people to see these two clubs as favorites. Atalanta was in Seria A and nobody will look up to them, because Roma is there and most people will even pick Roma instead of Atalanta.
However, this is football and we can only give our predictions on who will win the league but we cannot come to conclusion, because it is hard to predict the future since there will be some unforseen circumstances that will hinder our predictions from coming true due to natural phenomenon. Football is full of surprises and that is why no one can come to conclusion and beat his chest on his prediction coming true. Atalanta murdered the season, and I don't think I would love to predict who will be the winner of next season, until it competition starts.
Yeah true, Atalanta wasn't really considered as a threat to many of the teams there. Liverpool and Leverkusen facing each other at the finals looked like more likely. If Liverpool beat Atalanta, then the finals would probably be Liverpool vs Leverkusen and to be fair that would have been an expected finals as well, nothing shocking.
Atalanta not only managed to beat Liverpool to go to finals, but they also managed to beat Leverkusen to keep their run going as well. That definitely wasn't something they expected at all, feels like it is going to be something that did not really shock anyone. I personally believe that they are going to be quite good at the league next season as well, they were good, I think they will be even better.