Setien was sacked as following the European debacle, just seven months on from his appointment as Ernesto Valverde's replacement.
Setien lost 20 percent of his matches in charge of the Blaugrana, while they scored fewer goals per game than under Valverde – 2.0 versus 2.3 – even if their average possession increased to 68 percent, seemingly in line with the demands of supporters.
In an interview with El Pais conducted before president Josep Maria Bartomeu and the Barca board resigned, Spain great Vicente del Bosque asked the coach if he had brought "pure Setien" to Camp Nou.
"No, of course not," Setien said. "I have not been myself. I have not been able to, or I have not known [how to] – this is the reality.
"When you sign for a club with a dimension like Barca, you already know that things are not going to be easy despite having the best players in the world.
"The reality is that I could not be me, nor have I done what I had to do. It is true that I could have made drastic decisions, but they would not have fixed anything in a space as short as the one I had and in which everything was concentrated after confinement.
"Until [the break], the team was good. We were changing many things. We reached the break two points ahead.
"When we returned, we started well in Mallorca, but the situation was complicated and the trajectory of Madrid was extraordinary. In the end, the tension got the better of us.
"But, really, there are situations where, in another context and in other circumstances, I should have been different. There was no time either to think or to work.
"If I made drastic decisions, they could harm us. We had LaLiga, the Champions League. Then what happens against Bayern happens."
In Lisbon, Bayern became the first team to score eight times in a Champions League knockout game, while Barca conceded eight for the first time since losing 8-0 to Sevilla in the Copa del Rey in 1946.
The Catalan giants' oldest ever Champions League XI – at 29 years and 329 days – mustered just seven shots and their humiliation was completed when loanee Philippe Coutinho netted a brace.
Setien recognizes the harm done to his reputation but, now "comfortable at home" and "past the mourning", says he would have been sacked regardless.
"You are tremendously damaged," he said. "You go down in the history of Barca with that defeat.
"I take my percentage of the blame. Someday I will write about this. Afterward, I found out that the decision had already been made before the 8-2. I found out about everything."
Setien revealed in September he was taking legal action against Barca over the handling of his dismissal, claiming he was offered no compensation and the club failed to honor the terms of his contract.