Andy Robertson has written himself into Liverpool history as one of the club’s greatest-ever left-backs since arriving in 2017, but Milos Kerkez‘s arrival in the summer saw him instantly usurped by the new signing.While Liverpool may be just one point off the top of the Premier League table, the Reds’ performances have been of concern, especially in recent weeks.Having lost three consecutive matches for the first time in his career, Arne Slot must now find solutions for his stuttering side that is struggling to gel.Though the left-back position is far from Liverpool’s only issue, the introduction of Kerkez, who is clearly still a developing player, has been questioned by some.With Robertson reminding the Reds of his quality when coming off the bench against Chelsea – until the final moments anyway – Slot must now decide whether to stick with Kerkez as his first-choice or return to Robertson. Why did Liverpool sign Milos Kerkez?With Robertson reaching the age of 30 and not playing to the same standard as at his peak, Liverpool took the decision to bring in a fresh new face at full-back.The price for the 21-year-old came to £40 million, the second-highest fee the Reds have ever paid for a defender after Virgil van Dijk.At Bournemouth, he was voted the Premier League‘s best left-back of the 2024/25 season, providing six assists and scoring twice while playing all 38 league games for Andoni Iraola’s impressive team.Full of energy – only four players made more sprints than Kerkez in the Premier League last season – and with a final delivery to back his speed up, the Hungarian was seen as an ideal successor to Robertson. The right decision to start Milos Kerkez?Following a season in which the Scotland captain was often suspect defensively, Slot made the decision to put Kerkez straight into the starting XI.However, whether he should have done so is up for debate. Kerkez was a liability in his first couple of games but has improved.Despite the improvement, though, it has been levelled at Slot that Kerkez should have had to bide his time before going into the team, like Robertson did to overtake Alberto Moreno in 2017.While the Scot is no longer in his prime, he has arguably performed better than Kerkez when called upon this season.This could be down to him having played under Slot for longer, so he is more used to his methods.For example, the Dutchman often asks his full-backs to move infield rather than hug the touchline, something you can see that Kerkez wasn’t asked to do frequently for Iraola.At Liverpool, Robertson actually made more underlapping runs (39) than overlapping runs (33) over the course of the 2024/25 Premier League campaign, according to Opta.Over the last year, FBRef tells us Robertson was the better progressive passer, with 6.38 progressive passes per 90 minutes domestically compared to Kerkez’s 4.29.Meanwhile, the younger of the pair preferred to run with the ball managing 2.38 progressive carries per 90. Robertson made 2.38 per 90 in that respect.Statistics also showed Kerkez would receive the ball higher up the pitch, reflecting his role as a flying overlapping left-back.Kerkez received 5.31 progressive passes per 90, while Robertson received 3.91. Who should start for Liverpool currently?Slot has arguably been too quick to change a winning formula from last season, though his hand was forced in part.There isn’t a defining answer to who should be first-choice, but at the moment, bringing Robertson back in could help add stability to a Liverpool side which has undergone major changes.He already has steady on-field relationships with Cody Gakpo and Virgil van Dijk. Rekindling those would help bring back some fluency to Liverpool’s play on the left.Of course, this doesn’t mean Kerkez would be left out in the cold; Robertson has started twice and come on in four games already this campaign.The youngster could then be allowed time to develop before stepping up to replace his senior properly in the coming years.After all, like Florian Wirtz and Liverpool’s other signings, he signed a long-term contract. There is no need to rush the project when last year’s preferred XI won the league.