Iraola was left frustrated as City came from 1-0 down at half time to turn the game around and win 2-1, the Citizens controlling the second half to see them progress.
But Bournemouth were arguably the better side in the first 45 minutes, their press causing City problems, Evanilson handing the hosts the lead after 21 minutes.
It was a different story in the second half as Pep Guardiola’s substitutions made a difference, Erling Haaland equalising four minutes into the second period before Omar Marmoush gave City the lead.
_(Image: Richard Crease)_ Speaking to the media after the game, Iraola agreed that that the game turned at half time and got away from the Cherries.
“I think it has been a game with two very different halves,” he said.
“I think we were very good in the first half.
“We played the game we wanted to play but we couldn't keep the intensity levels that the game required for the second half.
“We gave them more time on the ball and when you give longer possessions to a team like City, probably they are going to punish you. That is what happened.”
Asked what changed at the break, Iraola told the Daily Echo: “The big change has been from our side in the way that we couldn't keep the same \[intensity\], especially pressing wise, we gave them more time on the ball and we were not as aggressive as we were in the first half and if we don't press, we don't win those duels.
_(Image: Richard Crease)_ “It's going to be difficult for our defenders because they will have to defend a lot against very good players.”
While they were poor in the second period, Iraola said he was pleased with their first half showing.
“Very happy with the first half, but when you don't win it's always not good enough,” he said.
“I think we've made the game very uncomfortable in the first half because we were not giving them the space. We were playing a lot in their half.
“They haven't had very long possessions but you have to pay a price also because you have to give a lot of energy in return.
“I think I tried to put players from the bench but I don't think we've improved a lot with the subs.
“But there are some players that I was perceiving that they didn't have the energy that the game needed to finish the game.”
There is not long for the Cherries to reflect on the cup defeat, as they host Ipswich Town in the Premier League on Wednesday night, April 2.