Timo Werner holds the key to Liverpool's next tactical development (Echo)

First it was a 4-2-3-1 system, the template almost identical from Jurgen Klopp's stint at Borussia Dortmund.

Then it was a 4-3-3, with Philippe Coutinho and Sadio Mane flanking Roberto Firmino, the trio combining brilliantly to dismantle Manchester City 4-1 at the Etihad Stadium among many other memorable, if inconsistent, results.

In his third season came the biggest change to date: Andy Robertson arrived, Mohamed Salah was signed, Trent Alexander-Arnold emerged and then Virgil van Dijk was acquired in January.

No longer reliant on pressing from the front to stop opponents from getting near a paper-thin backline, Liverpool's style drastically changed.

For the first time under Klopp, their back four could be trusted to perform as required.

Most recently, it was Alisson Becker and Fabinho who provided the next step up, leading to Jordan Henderson being freed up further forward, back to his number eight berth, and the Reds' defence to be able to stand higher up the pitch, safe in the knowledge their goalkeeper was adept at sweeping up.

From emotional, free-flowing and fluctuating to controlled, dominant and reliable, Jurgen Klopp's Liverpool have continually evolved tactically ever since the German arrived four-and-a half years ago.

So, for the Premier League champions in waiting, the obvious question is: what next?

Having seen his side develop from a team aspiring to make the Champions League places, to winning that competition and so much more, there is a strong argument to suggest Klopp will not want his players to evolve any more; that the job has been completed.

But that school of thought excludes two factors: firstly, teams now know how Liverpool play, and could work on ways to adapt before facing them (though that assumes that they are capable).

Secondly, and more significantly, it ignores the potential for new signings to be made this summer - or whenever the transfer window will now fit into the disrupted calendar - to freshen up the squad.

As Josh Williams discussed on the latest edition of the Analysing Anfield podcast, the Reds have been extensively linked with a move for Timo Werner.

The German forward could be central to answering that question of what the next tactical move from Klopp will be, with Werner also potentially evolving into the role of the replacement for one of the Reds' current front line in the coming years should he be signed.

Williams explained: “Klopp's been developing a lot at Liverpool, but that is as a result of the players Klopp has had at his disposal.

“They haven't always had elite offensive full-backs and a front three like that, or centre-backs who can cope with isolation.

“They've reached a point where Klopp will want to keep the tactical make-up as what they have got at the minute.

“That development has coincided with the players Klopp has got. Ultimately, your tactics have got to suit your players.

“Possibly that might change if Liverpool signed a player who was good enough to challenge that starting XI - say, for example, Timo Werner.

“Initially, not much will change but if Werner reaches a point where he is knocking on the door, Klopp would be forced into it.

“I'd expect one midfielder to come out at the expense of Werner coming in. That would lead you to a 4-4-2 or 4-2-3-1 formation.”

As the Reds look to maintain their recent performance levels and success, evolving again will be crucial - even if that alteration is only slight.

Stability is one thing, but for Liverpool to deliver a period of constant silverware, keeping ahead of the curve and evading the grasp of their rivals before they find a way to control them is even more important.

No doubt Klopp and his team - both coaches and scouts - will already be plotting their next move.