Barca won 2-1 on the night at the Metropolitano, but lost the quarterfinal tie 3-2 on aggregate.
Umtiti said on RMC Sport: "Everyone thought Barça would easily beat Atlético. I'm still disappointed with this Barça , especially defensively, because they've received two red cards in two games. They get into trouble, and in the end, it's usually pretty much the same story.
"And you realise that, yes, they take risks defending high up the pitch—the defensive line is the midfield line—but you realise that every time there's a challenge, they're late, and a delay costs a lot and ends up being a red card.
"That puts them in a difficult position, because I think if it had been eleven against eleven in both games, Barça would have won both, so I'm a bit disappointed. Atlético, in the end, is very solid.”
Umtiti also said of Atletico: “I think Atleti has a really good team, which we have certainly underestimated this year because in Spain we always respect Real Madrid and Barça more when they are successful. They are a very solid team defensively that does a lot of damage when they have space to run into.”
Finally, Umtiti once again criticised Hansi Flick's team: “Barça was a disaster. You play with ten men again and you're eliminated. Barça was among the favourites this year. They were respected in the group stage. People said they looked very strong in attack.
"It's true they were missing Raphinha, but they still had what it took to advance.”