Following a 4-2 loss to Leeds United, Iraola was seeking to bounce back against Monaco over the weekend but fell to another defeat as his side threw away a 2-0 lead.
Alexander Isak and Florian Wirtz put the Reds ahead but the side fell apart, losing 4-2 in what was a disappointing performance in front of the Anfield crowd.
Liverpool, who are tipped as title contenders, have no shown any real quality in preseason despite top stars returning to the fold which will only worry supporters who are keeping a close eye on Iraola and his new tactical system.
Speaking after the defeat, Van Dijk revealed that he and the squad are still getting used to life under the Spaniard who took over from former manager Arne Slot this summer.
"It definitely feels like a bit of a transition, for sure. It is down to everyone associated with Liverpool to make sure we are building something that will be successful for years to come.
"This year, we want to be successful, but there is a lot of work still to be done. We all know how difficult it is to be playing in the Premier League, the League Cup, the FA Cup, and the Champions League, so we need everyone at their best.
"Nothing to take away from Arne (Slot) and his staff, we had an amazing time together, obviously last year a disappointment. This year we have a new manager who has new ways of preparation, so we have to adapt to a new staff, and different training methods. But I liked working under Arne and I am sure I will like working under the new manager."
Liverpool face Como next in their final preseason match before kicking off the new Premier League season against Newcastle where fans will hope the side have adapted to Iraola’s style which hasn’t quite worked in its early stages.