The focus was specifically on the vulnerability from set-pieces and how Liverpool's failure to get a deal done for Southampton centre-back Virgil van Dijk would continue to cost them. That was Redknapp's take anyway -- he insisted that Van Dijk would have solved all of Liverpool's problems.

Carragher meanwhile, was adamant that one man alone would not make that much of a difference, particularly on set-pieces when the responsibility is a collective one.

Redknapp's view on it seemed overly simplistic at the time, whereas Carragher's well thought out assessment made perfect sense. One man can't make that much of a difference; it's not like he can head away every set-piece, can he? Actually yes, he can as it turns out. We saw that on Monday night when Liverpool won 2-0 at Crystal Palace.

Redknapp was right. He was roundly mocked at the time, but his apparent "hot take" has been proved to be an astute observation. One man has essentially solved Liverpool's defensive issues. Others are doing their jobs to a high standard too, but Van Dijk was the catalyst. The Reds' aren't a soft touch anymore.

Van Dijk's monstrous display at Crystal Palace proved Redknapp's point emphatically. The Dutch colossus seemed to head away every ball that was played into Liverpool's penalty area and bossed the game without even breaking sweat. Palace striker Christian Benteke struggled to even get a touch of the ball and was bullied throughout -- which is not something you'll see very often.

The "Van Dijk effect" can be summed up in one passage of play in stoppage time. Liverpool were defending a one-goal lead and while they weren't exactly hanging on, one mistake or lapse in concentration could have seen them drop two points, which even at this early stage of the season could be seen as catastrophic given the likely pace Manchester City will be setting once again.

Supporters' nerves will have been jangling when substitute Adam Lallana conceded a needless free kick out wide, allowing Palace to throw all the big men forward for one final push for an equaliser. How often have we seen Liverpool capitulate in these circumstances? The answer is: too often.

But what happened next should warm the hearts of Kopites everywhere though, as well as striking fear into any future opponents.

Palace swung in the free kick towards their towering striker Alexander Sorloth but Van Dijk beat him to it and headed it away for a corner. When the corner came in, he headed that away too. More specifically, he headed it straight to the feet of Mohamed Salah to launch a counter attack; Salah found Sadio Mane and just like that 1-0 became 2-0 within a few seconds.

Virgil van Dijk holds off Aaron Wan-Bissaka in Liverpool's 2-0 win over Crystal Palace on Monday. Photo by Glyn KIRK / AFP

It's not that much of a stretch to suggest that Liverpool are more dangerous from the opposition's corners than they are from their own these days. It must be reaching the point where opponents will have to seriously think about how many men they push forward on set-pieces, because Liverpool's speed and skill on the counter is so deadly.

The key to it is having someone who can clear the set-piece and give the speedsters the change to break. Van Dijk is as good as there is at doing that, while the arrival of the equally imposing Alisson Becker in goal should also help.

It isn't just Van Dijk's aerial ability that has made all the difference to Liverpool though, it's the presence and calm that he brings too. As Carragher said after Monday night's game, "he has no weaknesses." Great players can often elevate the performances of those around them and Liverpool's defenders have all benefitted hugely from Van Dijk.

Young Joe Gomez has every attribute needed to be a genuinely top-class defender in the future but he lacks experience and occasionally it shows. Van Dijk is the perfect partner for a player like Gomez, as he's constantly talking and helping all of his teammates through the game. Gomez was outstanding against Palace, so Joel Matip and Dejan Lovren are really going to have to fight to get back in the team.

Liverpool will always score goals, but opponents often feel that if they can ride their luck and limit the Reds' much vaunted front three to maybe just the one goal, they'll always have a chance of nicking something at the other end.

That's still the case -- as it is with any team, no matter how good they are -- but since his £75 million January arrival, Van Dijk has more clean sheets than any other Premier League defender.

The improvement has been marked and there is no doubt that Van Dijk has done exactly what he was brought in to do. It seemed like a lot of money at the time but it doesn't any more. You don't always get what you pay for, but Liverpool certainly did with Van Dijk.