Jurgen Klopp described Pierre-Emerick Aubameyang as a player with "no real weaknesses" ahead of a meeting between Liverpool and Arsenal in August 2019. Klopp, his former coach at Borussia Dortmund, lauded his "incredible" development into a "goal machine".
Aubameyang was at the top of his game at the time having scored 31 goals in his first full season at Arsenal and hit two in two games at the start of his second. But there are question marks hanging over the striker as he prepares to face Klopp again on Saturday.
It has been a difficult season for Aubameyang. The 31-year-old signed a lucrative new contract in September having played a crucial role in Arsenal's FA Cup win six weeks earlier but by the turn of the year he had only scored three times in 14 Premier League games.
A two-goal performance against Newcastle in January was viewed a possible turning point but his mother fell ill soon afterwards, causing him to miss a string of fixtures, and while there was a hat-trick against Leeds on his return, he is still struggling to find his rhythm.
Aubameyang has not helped himself in that search for rhythm recently, of course. His lateness prompted Mikel Arteta to drop him for the north London derby win over Tottenham and since then there have been poor displays against Olympiakos and West Ham.
Indeed, in the frantic 3-3 draw at the London Stadium before the international break, there was even the rare sight of the striker being substituted as Arsenal chased an equaliser.
The combination of his new contract and his status as club captain means expectations of Aubameyang are higher than ever among supporters - and understandably so.
At 31, some have even questioned the wisdom of giving him a new long-term deal after the costly saga that unfolded around Mesut Ozil following his contract renewal in 2018.
But Aubameyang's struggles this season must be viewed in the context of Arsenal's as a whole.
Arteta talked about Arsenal missing Aubameyang's goals in the first half of the season but he was not helped by the dearth of creativity behind him. The Gunners struggled to even get the ball into the final third at times, let alone into the opposition box.
Aubameyang may have only mustered three Premier League goals during that period but according to Opta, he actually performed in line with his expected goals; a clear indication that the biggest issue was a lack of service rather than wasteful finishing.
Aubameyang simply wasn't getting enough chances. His confidence suffered but he wasn't the only forward struggling. Up until Christmas, Arsenal ranked 15th in the Premier League for chances created. Aubameyang was in fact their joint-top scorer along with Alexandre Lacazette.
It was only after Christmas that Arsenal finally clicked and started creating more opportunities. Emile Smith Rowe's introduction to the team was a major factor in the improvement and Martin Odegaard's arrival from Real Madrid provided another boost.
With two natural playmakers added to the side since Christmas, Arsenal have jumped from 15th to fifth for scoring chances and it is no coincidence that Aubameyang's output has improved too.
The striker is having more touches in the opposition box and having more shots. As a result, he has gone from averaging 0.2 goals per 90 minutes before Christmas to 0.7 per 90 minutes since.
A return of six from his last eight Premier League appearances looks good on the face of it but those goals have come in clusters - two against Newcastle and three against Leeds - and there has been inconsistency in terms of playing time and performances.
His subdued showing from the right against West Ham, during which he failed to register a single shot on goal or create any chances, re-opened the debate over his best position.
But while some believe he is better suited to the central striking berth, it is worth remembering that much of his best work has been done from wide positions at Arsenal.
In fact, Aubameyang has started more games there than he has through the middle since his arrival at the club in 2018 and it hasn't stopped him scoring 63 Premier League goals in 109 appearances - a total only beaten by Mohamed Salah in the same timeframe.
The issue for Aubameyang is that he is struggling to establish rhythm and build his confidence back up at a time when Arteta has a wide array of attacking options at his disposal.
Odegaard has become a key figure at No 10 and that heightens the competition for places in the wide positions.
Smith Rowe and Bukayo Saka have been outstanding in recent months, while Nicolas Pepe and even the much-maligned Willian have shown signs of improvement recently.
Those players do not carry the same penalty-box threat as Aubameyang, of course, but they do have other attributes - creativity and youthful energy in the cases of Smith Rowe and Saka, one-on-one ability in the case of Pepe - that give them an edge on Arsenal's captain in different ways.
Aubameyang does not offer as much in general play as others, meaning his contribution tends to be smaller when he is not scoring, while the in-form Lacazette gives the side a different dimension up front. The Frenchman has scored in each of his last three starts and his link-up play in deeper areas has been invaluable too.
Aubameyang is capable of linking the play himself, of course, but he is better suited to playing on the shoulder of the last defender, running in behind rather than dropping back to create space for others. Recent evidence suggests that's not what Arteta wants from his central striker right now.
It will be interesting to see how Arsenal's attack is configured against Liverpool on Saturday. The circumstances dictate Aubameyang is perhaps not the certain starter he once was. But Arteta would be wise to stand by him. The best way to find consistency is to play consistently. And Arsenal need him at his best..