The defenders have both become integral parts of Jurgen Klopp's Reds side, with their energy and attacking quality key to the manner in which the team operates.
Gerrard, who is now the manager of Rangers, was asked about the influence of the duo and said that at the moment there aren't many better in the world than Robertson and Alexander-Arnold, per Paul Gorst of the Liverpool Echo:
"It's not a question of 'how good can he be?' because he is already there. What we have in Trent and Robbo (Andy Robertson) now, straight away, you would put them in the world-class bracket. They are up there with the best players in their position, worldwide. So there's no point saying how good could they be because they are already there.
"The thing for Trent now is can he maintain that consistency for as long as he can? Because he can go on and be whatever he wants to be. What I would say is he is already there, and we, as Liverpool fans, are blessed to have these two full-backs in the position because they are absolutely flying."
The attacking potency of the pair was summed up by BT Sport:
There also appears to be healthy internal competition between Robertson and Alexander-Arnold. The duo had a Twitter exchange following the recent 3-1 win over Manchester City in the Premier League:
Sky Sports Football examined what was a pinpoint delivery from the Scotland skipper to set up Mohamed Salah:
The pair are indicative of what is expected from the modern full-back for an elite side.
On the left, Robertson is a bundle of intensity and aggression when he carries the ball forward, while Alexander-Arnold covers every blade of grass on the right. With the ball at their feet, they are both incredibly consistent and it's that reliability of delivery that sets the pair apart from so many others. They have provided eight assists in all competitions between them.
While they play on opposite sides of the field, there does appear to be a natural chemistry between the pair too, as picked up on by football writer Daniel Storey:
For the Liverpool attackers, having such high-quality players in wide areas is a dream, as they can make darting runs into dangerous areas and be aware that a top-class cross is on the way.
Robertson and Alexander-Arnold are already Liverpool icons, having helped the team to UEFA Champions League glory last season. They are well on their way towards adding to that legacy too, with the Reds eight points clear at the top of the Premier League, as they seek their first title in 30 years.