The Reds won 3-0 as Luis Diaz (2) and Darwin Nunez struck before halftime.
Iraola later remarked: "I think they were better when it mattered, when the game is on the line. We had a disallowed goal, other chances, and when the game was very open they made the difference when it clearly mattered. The start wasn't very different but the things you do after 3-0 are not very valuable.
"We feel like we were doing well, having our chances, and after the first goal we lost the intensity, focus and you cannot allow this. The momentum changed and probably a lack of experience, we are a young team, we need to calm the game after conceding the first goal."
On his booking for dissent, Iraola shrugged: "I think it has been a misunderstanding and I hope we can overturn it. They booked me for asking for a yellow card but I was asking for an offside. I wanted not an advantage but an offside and there was nothing happening where I could ask for a yellow card. I don't know how this works, here I don't know.
"The problem is it's not the first game where we have a lot of chances but don't get the goals we expected, especially at this level you have to take your chances when you are playing well because for sure they will punish you. We did more than enough to score.
"It is difficult for us to accept. What you do in the boxes makes the difference and we need to improve certain things."