Joel Matip is the first glimpse of Jurgen Klopp's vision for Liverpool
Liverpool's agreement to sign centre-back Joel Matip on a free transfer represents the first significant step in manager Jurgen Klopp's transformation of his squad.
It is a reminder that despite Klopp's staunch defence of the players he inherited -- and talk of his players having an "agreement for one year" rather than feeling constantly under threat -- things are going to change at Anfield in the summer if Klopp is to put his stamp on the club.
Matip, who joins from Schalke at the end of this season, is the second addition for 2016-17 after Marko Grujic joined from Red Star Belgrade, but the first definite challenge to the status quo. While Grujic, 19, is one for the future, Matip brings considerable World Cup, Champions League, Europa League and Bundesliga experience, and is destined to slot in at centre-back alongside Dejan Lovren, Mamadou Sakho or Martin Skrtel.
Strong in the air, two-footed, comfortable in possession and with decent pace, Matip can also play as a defensive midfielder and fill in at right-back. And at 6-foot-4, he will become the tallest member of Liverpool's relatively diminutive squad.
Having attended the same school that produced Germany's 2014 World Cup winners Mesut Ozil, Manuel Neuer, Benedikt Howedes and Julian Draxler, Matip made his Bundesliga debut for Schalke in November 2009, scoring the equaliser in a 1-1 draw with Bayern Munich (then managed by Louis van Gaal) and was named man of the match.
Matip played 20 times that season, mostly in midfield, before shifting between midfield, full-back and centre-back the following season. Since 2011-12, he has established himself at centre-back and is closing in on 200 Bundesliga appearances.
The son of Jean Matip and brother of Marvin Matip, both Cameroon internationals, Joel opted to follow suit rather than represent Germany, the country of his birth. He has 27 caps to date and has already appeared in two World Cups.
As far as Liverpool are concerned, what is not to like?
And so Klopp's rebuilding begins. Whatever the uplift in mood around Anfield and Melwood, however much energy has been injected into Liverpool's performances as they have played in the image of their new master, plenty is unchanged.
With a 43 percent win record in all competitions, compared with the 50 percent of predecessor Brendan Rodgers, results under Klopp have taken a slight downturn -- albeit with injuries and a willingness to take a step back to take two forward. The Reds are still vulnerable playing at home, they don't score enough goals, defend too sloppily, lack consistency and struggle to perform for a full 90 minutes.
Those defensive shortcomings stretch back to as long ago as 2013-14, when they went close to winning the Premier League title. That vulnerability at the back was also an area in which the transfer market offered Klopp's only effective remedy, because his acknowledgment of weaknesses there had not led to a significant improvement.
In attack, by contrast, he has set great store by using Roberto Firmino as a false No. 9. Klopp has awaited the likely improvement that would arrive when Daniel Sturridge would return from injury and have regular involvement for the first time since the German took over -- as he will hope is now the case.
After also losing Danny Ings to a knee injury in his first training session in charge, and subsequently Divock Origi and Philippe Coutinho, Klopp had no great wish to block his star forwards' returns by recruiting short-term replacements. It was in this context that he saw no value in Shakhtar Donetsk's asking price for the prolific Alex Teixeira.
In defence, the issues ran deeper than a short-term lack of personnel as the ailments mounted over Christmas. Drafting in Steven Caulker on loan pointed also to the manager's broader intentions after despairing of his defenders' fallibility under the aerial ball.
"We want to play good pressing, we want to press the opponent and so they have to play long balls," Klopp said. "If they play long balls, you need people in the last line who can help you with headers." The 6-foot-3 Caulker can do that and has done so in his fleeting appearances thus far.
If his January loan could bolster the side without undermining Klopp's yearlong "contract" with his players, so, too, can a pre-agreed arrival for the end of that year. Kolo Toure, who turns 35 in March, is out of contract by then, and the popular Ivorian -- so useful to Klopp as a stand-in this winter -- is nearing the end of his shelf life as a regular starting option.
The arrival of Matip, a man 10 years his junior, ensures first and foremost that four internationals will be available at centre-back. Lovren, Sakho and Skrtel -- perhaps also Caulker -- have the remainder of that gentleman's agreement with the boss to avoid being displaced.
This season, the Cameroonian has Schalke's best statistics in interceptions, blocks, clearances and headed clearances, ranking in the Bundesliga's top 10 across those categories combined. Matip also dribbles more than any of Liverpool's centre-backs and boasts 17 goals for the Gelsenkirchen club, 16 of which have come from set pieces.
He has missed only three of Schalke's 29 matches this season, all in the Europa League group stage, chipping in with four goals and an assist -- so Matip is not moving to England to kick his heels.
And it is not only Liverpool's centre-backs who ought to take note. Klopp's instinct has been to limit his academy graduates' exposure to first-team action, putting their development before short-term needs. As laudable as that is, it has taken some of the heat off his regular first-team picks.
Their places have been reasonably safe, no matter how underwhelming the Reds' form and results. There has been little sense that places are up for grabs to play at Wembley in the Capital One Cup final on Feb. 28, despite an ordinary 2016 so far for most of those likely to be involved.
Liverpool will need to sustain heights they have hit only fleetingly this season if they are to see off Manchester City and earn Klopp an early piece of silverware, or pursue their other attainable target, the Europa League. The first sign that the man in charge is handpicking players to guarantee those levels are hit next season can only focus minds before the staging posts to come and the likely summer rebuild beyond.
Tom is ESPN FC's Liverpool correspondent. Follow him on Twitter @writertombell.