Goals from Kieran Morrison, Dominik Szoboszlai, Federico Chiesa and Lewis Koumas saw Iraola's side come from behind to beat their Premier League counterparts at GEODIS Park, though the head coach was more focused afterwards on fitness levels and an injury to Joe Gomez than the result itself.
"I think it was different halves. Especially, they were a lot stronger in the first half. We kind of balanced both teams, and you could feel the difference. A lot of things to correct, obviously, it's the first day. You could feel the heavy legs, the players have been training. So, we lacked some freshness. But it will give us a good starting point to improve things," Iraola told Liverpoolfc.com.
"Probably the worst news has been straight away the injury of Joe [Gomez]. We were happy because we were kind of going through all the training without losing any player. Unluckily for us, straight away we've lost Joe."
Iraola also explained the thinking behind resting Jeremy Jacquet, who was absent from the squad.
"With Jeremy, we decided to take it easy with him. He has been a lot of months without playing with a shoulder injury. So, I think we are going to take it easy with him. He will play probably the last game of this US tour and he will have time to have minutes."
On the quality of the contest itself, Iraola pointed to conditions and fatigue as much as anything tactical.
"It was difficult to put rhythm into the game. I think both teams were lacking some freshness and it was also humid. The pitch was quite slow. We had some good spells on the ball. I think we lacked a little bit of intensity. You can feel the timing is still not there. We have to work a lot more but it's a starting point."
Asked about his side's response after falling behind, the manager stressed that using the minutes productively mattered more than the result.
"It was a matter of using the game to push ourselves and to go back to the rhythm that we should have. You play 45, 60 [or] whatever the minutes you play, use them properly. It doesn't matter the result but keep pushing, don't relax, get used to not playing too comfortable. We still have a lot of things to improve."
Iraola confirmed that Alexander Isak, Florian Wirtz and Ryan Gravenberch have already reported for pre-season in Chicago and will begin training with the squad from Sunday, with two further matches to come on Liverpool's US tour.
"I hope we use them properly and we go [forward] improving slowly, slowly the things that today didn't work," he said.