Carragher, speaking on The Overlap Fan Debate, was careful not to dismiss Iraola's qualities but drew a clear distinction between what he has achieved at Bournemouth and what will be demanded at Anfield.
"No one can say you don't love watching Bournemouth play," he said.
"If they're on the TV, you're watching them and you think, 'oh, we're going to see a good game.'"
But he then made the central point.
"The point is with how he plays. I actually said — and I can't go back on it — that I think Iraola would be making a mistake leaving Bournemouth, because the next thing he needs to prove is that he can manage that brilliant, high-intensity football on a European stage. He needs to prove he can manage a European season in the way that he manages his players physically."
Carragher's concern centres on load management. Iraola's teams have historically tended to drop off in the second half of seasons, a pattern he attributed to the physical demands of his pressing system. He noted that last season — when Bournemouth finished sixth and qualified for the Europa League — was the first time one of his sides had genuinely sustained its level in the final months of the campaign.
"When you're in Europe, you've got to rotate, you've got to manage the players physically. I thought that would be the next step for him, just to prove he can still produce the goods in a European season, and then he'd be ready for his next move."
He drew a parallel with Jürgen Klopp's own developmental path, suggesting that the German had needed a full European experience at Borussia Dortmund before being truly ready for a club of Liverpool's scale.
"It almost feels like it's a year... not too early. But Klopp was manager of Mainz and had to go and prove at Borussia Dortmund that his style of football can work in Europe. That still needed to be proven by Iraola."
Carragher also questioned whether Liverpool's squad — several of whom struggled with injuries and fitness across the 2025-26 season — can physically sustain what Iraola will demand.
"Does the intensity have to drop off so you're not getting the full Iraola? You're getting too many injuries, you've got too many games, then he's got to be more of a footballing manager. You're also on the ball more at Liverpool than you are at Bournemouth."
Liverpool confirmed a verbal agreement with the 43-year-old on Tuesday, with a formal announcement expected before the World Cup begins. Iraola is set to sign a two-year deal and intends to bring Bournemouth assistants Tommy Elphick and Shaun Cooper with him to Anfield.