It’s not a crisis, not yet, but Liverpool’s run of three defeats in a row is reason to take stock. It’s true that the two league games in that run were both lost via last-minute winners, and that in isolation these three games could be explained away relatively easily. But context matters, and the truth is that while Liverpool won their first five league games of the season, they did not play well in them.

New players are struggling to settle and Arne Slot’s rejig of the formation has not really worked, while a number of regulars look out of sorts. Last season Liverpool won the league playing extremely controlled soccer, making 2-0 almost a trademark scoreline, establishing their lead and then running the clock down. This season there has been none of that, no sense of playing within themselves. They’ve been extremely open through midfield and most of their wins have come through late goals. There’s been an unexpected wildness to them, almost as though Slot is going through his transition a season late.

Introducing any new player to a side is fraught with potential issues. The player has to learn their environment and their teammates have to get used to them. Even in the best cases, dropping a new player into a functioning side will lead to a slight short-term drop-off. Liverpool avoided that last summer by signing only Federico Chiesa. Adding five new players, as they did this offseason, means a lot of disruption. And, of course, this is a squad dealing with the tragic loss of Diogo Jota. Mohamed Salah’s on-pitch tears after the final whistle of the opening game of the season were a reminder that this is a club in mourning. Soccer keeps going, as it must, but the impact of Jota’s death is unpredictable and may be felt for a long time yet.

At first it seemed the biggest tactical problem was the switch from 4-3-3 to 4-2-3-1 to accommodate Florian Wirtz as a central creator. The balance given by a central trio of Ryan Gravenberch, Alexis Mac Allister and Dominik Szoboszlai was gone, not helped by the fact that Mac Allister still doesn’t quite seem back to his best after a muscle injury, while Wirtz is yet to settle. But in recent games, Slot has returned to last season’s trio, switching back to 4-3-3, and many of the same problems have remained. Liverpool’s centre-backs keep being isolated, a situation exacerbated by Ibrahima Konaté’s loss of form.

So what has changed? Why isn’t the centre-back pairing and midfield three that were so effective last season suddenly functioning? The answer is twofold. First, Liverpool’s press has stopped working as it once did. The 2020-21 season, in which Liverpool finished a distant third to Manchester City, offers a warning of what happens when that misfires. Second, and more intriguingly, new full-backs Miloš Kerkez and Jeremie Frimpong are very different from Andy Robertson and Trent Alexander-Arnold.

English soccer struggled to understand Alexander-Arnold. As a youth player he had been a midfielder and his gifts were those of somebody who would usually play in midfield. He is arguably the best passer of a ball currently playing for England, which is what led many to argue that he was wasted at full-back, and that he should be used in midfield. Attempts to play him there, though, were unconvincing, as though his years on the right of a back four had somehow rendered him unsuitable for a more central role.

And yet he wasn’t a particularly good defender, at least if that is defined in the traditional way. He wasn’t great at marking, and he was, by the standards of top-level full-backs, relatively easy to dribble past. He is sui generis, which is one of the reasons he has never really looked convincing while playing for England. International soccer, given the lack of time available to coaches, prefers plug-in-and-play footballers, right-backs who play like right-backs.

But Alexander-Arnold has two attributes that Liverpool are severely missing at the moment. His rapid and accurate 30- and 40-yard passes were often what released Salah, but his passing generally was central to Liverpool’s buildup play. Probably even more important, though, was his capacity to invert into midfield, to become an additional holding player alongside Gravenberch. Frimpong, who was a wing-back at Bayer Leverkusen, is a very different sort of full-back. He runs with the ball rather than passing it, and his natural inclination is to go on the outside not the inside. Given Salah wants to cut inside, that may work eventually. But for now, Liverpool are missing both the balance Alexander-Arnold brought and his capacity to unleash Salah, who has had a very quiet start to the season and is yet to forge a relationship with any of the new forwards.

Any side making as many changes as Liverpool will inevitably have teething problems, but what is notable at the moment is that the issue is less the players who are there than one who has left. Alexander-Arnold’s unique range of abilities will not easily be replaced.

• This is an extract from Soccer with Jonathan Wilson, a weekly look from the Guardian US at the game in Europe and beyond. Subscribe for free here. Have a question for Jonathan? Email soccerwithjw@theguardian.com, and he’ll answer the best in a future edition.