There are understandable reasons for Liverpool typically avoiding mid-season signings, not least due to the lack of value in the winter market.
It would be no stretch, either, to suggest even those within the club’s recruitment staff would have anticipated a slower adjustment period for the £50 million signing from Porto.
Liverpool have only made seven January signings during Klopp’s reign. Three of those – Steven Caulker, Ozan Kabak and Ben Davies – were emergency deals and another – Marko Grujic – was one for the future, loaned out again immediately.
For Diaz, any contribution between day one and the end of the season should have been considered a bonus; the second half of the campaign an extended bedding-in process for a player who could eventually settle during pre-season.
That was certainly the case for Takumi Minamino, albeit the Japanese arrived during a turbulent time as lockdown life struck as he moved from Austria to England, unable to speak the language.
But while Diaz also headed to Merseyside with a flimsy grasp on English, he defied expectations and hit the ground running.
Undeterred by the language barrier, the Colombian built bonds with Curtis Jones and Harvey Elliott, while the club’s Spanish-Portuguese contingent played a vital role in his adjustment.
He teed up a goal for Minamino on his debut and scored his first goal in only his second start, adding to that smart finish in the 3-1 win over Norwich with a brave header against Brighton less than a month later.
There were further goals against Benfica, Man United, Villarreal and Tottenham, and assists against Benfica, Man United, Everton and Aston Villa.
He dazzled against Chelsea in the League Cup final, Man City in the FA Cup semi-final and then Chelsea again in the FA Cup final.
Diaz swiftly established himself as a key player who could thrive in the big games, with his mid-season impact only rivalled by Virgil van Dijk when it comes to Klopp’s January signings.
“He gets our football, 100 percent,” Klopp enthused after Diaz’s Man of the Match display in the FA Cup final.
“We thought we saw that at Porto, but that it really is like this, I feel lucky as well to be honest.
“He fits like a glove to our football, and that’s really, really special.”
The manager’s praise sums up so much about the winger’s immediate impact and the triumph felt among Liverpool’s hierarchy.
Diaz was not only identified for his end product on the ball – though 16 goals and six assists in 28 games in the first half of the season at Porto were certainly persuasive – but equally his infectious work rate off it.
His heatmap for the Premier League highlights his dominance on the left side of attack, but also a reliable presence in the left-back zone, covering and interchanging well with Andy Robertson:
It is a rare blend, and particularly for a player who has worked within Klopp’s setup for such a short time, which makes him ideal for Liverpool.
Beyond the rabona touches in mid air, the no-look passes on the wing and the devastating shots from distance, the Reds have unearthed a player whose flair is counterbalanced by sheer humility.
It has not all been smooth sailing, with Diaz fading throughout the Champions League final as he struggled up against Dani Carvajal, but he quickly put the disappointment behind him.
The off-season has seen him return to his native Colombia, reconnecting with old friends and locals in Barrancas and even playing in an exhibition game for the reopening of the Estadio Federico Serrano Soto in Riohacha.
He is a special character who, as Klopp rightly declared, “fits like a glove,” and it is incredible that this is only the start.
It is safe to say this is a seismic summer for Liverpool in terms of the makeup of their attack, with Mane joining Bayern Munich and Darwin Nunez arriving as a club-record signing from Benfica.
That it comes during the official handover of sporting director duties from Michael Edwards to Julian Ward may not be seen as ideal.
But the impact Diaz has made at Anfield has certainly helped expedite an evolution in the final third; were it not for his emergence as a key player already, the concern over Mane’s exit would have been magnified.
As it stands, though, Liverpool find themselves comfortable with a new-look group with Diaz, Nunez and Diogo Jota refreshing the unit alongside Salah and Roberto Firmino.
Much is up in the air heading into the new campaign, of course, not least who will start as Klopp’s new first-choice forward line.
But there is no doubting that, like Salah, Diaz will be one of the first names on the teamsheet from opening day at Fulham – especially as he benefits from a summer off and a mid-season break after Colombia failed to qualify for the World Cup.
It would be wrong to heap the pressure on Liverpool’s No. 23 despite his emphatic start.
But there is every confidence that Diaz will only go from strength to strength in his first full season.
