There were plenty of post-mortems after last season. Tactics, pressing intensity, squad depth, mentality — you could take your pick depending on which pundit you happened to catch. But former England winger Chris Waddle reckons everyone has been looking in the wrong place. For him, the answer was staring us in the face all along: the middle of Liverpool's defence.

And when you look at the numbers, it is hard to argue with him. Fifty-three Premier League goals conceded across 38 matches. The worst defensive record Liverpool have posted in the modern era of the top flight. A fifth-place finish. A sacked manager. The dots are not difficult to join.

Now new head coach Andoni Iraola is inheriting that problem — and Waddle, speaking to OLBG, has offered him a fairly direct message about where to start.

"Last year, while many pointed to tactics, I believe the real issue was the middle of the defence," Waddle said. "If they can strengthen that, there's no reason why Liverpool can't challenge again this season."

The timing matters too, because the options available to Iraola at centre-back are not exactly abundant right now. Ibrahima Konate has departed for Real Madrid on a free transfer, which is a blow in itself. Teenager Giovanni Leoni remains unavailable as he works through a long-term knee injury. The arrival of 21-year-old Jeremy Jacquet from Rennes for £60 million adds genuine quality and youth to the equation, but the picture behind him remains thin.

Which brings everything back to Virgil van Dijk. The Liverpool captain, 35 years old, started every single Premier League and Champions League match for the club last season. That kind of reliability and leadership carries obvious value, and Waddle is not dismissing him entirely. But he is raising the question that a lot of supporters have been quietly asking themselves for a while now.

"Van Dijk obviously still has a big influence on the Liverpool squad, so you might keep him for another year and use him in specific games," Waddle said. "But again, if he's performing well, you play him. But I just think that central position is the key issue for Liverpool."

The key word there is pace. Or rather, the gradual erosion of it. Van Dijk has always been a reader of the game — that footballing intelligence is what set him apart from the moment he arrived at the club. His technical quality remains. But Waddle argues that when the Premier League's relentless pace begins to expose that single missing yard, it does not matter how experienced or composed you are.

"He's not going to get any quicker," Waddle said plainly. "He's always read the game well and has always been technically sound. But when you lose that yard of pace, it's difficult in the Premier League. The league is so quick. I thought that last year, regardless of who his centre-half partner was, they struggled."

That last part is worth sitting with. Regardless of who his partner was. Because that framing shifts the conversation from a question about depth to a question about the senior man himself. It is a view Waddle is entitled to hold, and one that deserves more than a dismissive response from the Liverpool faithful.

Iraola, for his part, arrives with genuine credit in the bank. His work at Bournemouth was remarkable by any reasonable measure, and Waddle is fulsome in his praise.

"Andoni Iraola has done a marvellous job, nobody can question what he achieved at Bournemouth," he said. "He likes to play on the front foot and, as a good tactician, he prefers an attacking style that suits the way Liverpool play and what their fans want to see. I think they crave excitement, they want to see the team attacking. I think he will definitely do that."

The question of whether the players available to him are good enough is the one that hangs in the air. Iraola's philosophy is clear, his ambition is not in doubt, and his understanding of how to get the best from his squad is well evidenced. But philosophy cannot paper over structural weakness.

Waddle also touched on Milos Kerkez, the left-back who joined Liverpool last summer after working under Iraola at Bournemouth. The assessment is balanced — Waddle does not think the defensive side of Kerkez's game has ever been his strongest suit, but he believes the Irishman's energy and attacking instincts make him perfectly suited to the way Iraola wants his side to play.

"Iraola knows how he wants to play," Waddle said. "He's going to get the best out of him, have him play on the front foot, and get him attacking down that wing. I'm sure that's what he'll be doing and I think we'll see a new player."

That is an encouraging thought, and there are reasons for genuine optimism about what Iraola can build here. But if the defence creaks again when the serious tests arrive in autumn, the conversation will come back to exactly the point Waddle is making now.

Iraola knows what he wants his Liverpool to look like going forward. The pressing question is whether he can also sort out what happens when they do not have the ball — and whether the transfer window gives him the tools to do it.