When William Saliba arrived at London Colney in summer 2020 to belatedly begin his Arsenal career, the view from the more cynical corners of the training ground was damning.

Saliba had been signed from Saint-Etienne for €30 million in 2019 and immediately loaned back to the French Ligue 1 club for a season, by the end of which Mikel Arteta had replaced Unai Emery as head coach and the usual turnover of backroom staff had occurred again.

The squad was also in a state of flux by that stage, with Arteta determined to stamp his authority on a group which had lost direction and discipline. There was a desire to refresh his options with youthful, hungry players and it seemed logical that a centre-back then barely 20 years old, whom the club had invested a large amount in a year earlier, would form a key part of his plans.

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Yet sources told ESPN that during the 2020-21 preseason there was scepticism over whether Saliba would make the grade. Multiple players -- none of whom are still at the club now -- were said to have described Saliba somewhat dismissively as "League One-level," the third tier of English football, citing poor positioning and a tendency to jump into the tackle. There was a recognition that the young centre-back had time on his side to improve, but Arteta and his staff came to the conclusion that his development should take place elsewhere -- only for a clerical error to deny him a second loan spell back at Saint-Etienne.

Despite Saliba being forced to stay in north London until January 2021, there was no revision of their initial judgement. He languished in the reserves -- omitted from the Europa League group stage squad in a further withering assessment of his credentials -- until a midseason loan move to Nice. Saliba was reported to have suffered personal issues, including family bereavement, during this period and by the time he was sent on loan once more for the 2021-22 season, this time to Marseille, his career at Arsenal looked over before it began.

But his form at Marseille was sensational as he landed a call-up to the senior France national team in March and was named the Ligue 1 Young Player of the Year at the end of the season. Continuing where he left off, Saliba was finally given his chance at Arsenal this season and has not looked back, starting all 24 Premier League games as the Gunners have exceeded all expectations in leading the title race into March.

Together with Brazilian Gabriel Magalhaes, he has formed a centre-back pairing Arteta describes as a "happy marriage," part of the second-best defensive record in England's top flight (behind Newcastle) and the bedrock of Arsenal's present buoyancy.

Saliba's individual transformation has been nothing short of staggering. He has 186 ball recoveries in the competition, the fourth-highest total behind West Ham's Declan Rice, Manchester City's Rodri and Tyler Adams of Leeds United. No Arsenal player has touched the ball more (1,798) and his pass completion percentage (95.8%) is the highest in the league of anyone to play more than eight games, underlining how effective he can be in helping to build the Gunners' attacks from the back.

The once uncertain and coy demeanour has been replaced by a surefooted composure which has made him one of the league's standout centre-backs this term, defying those early training ground critics to become a cornerstone of the team. So much so that Saliba is next in line after forward Gabriel Martinelli signed his new contract and Arsenal agreed terms for Bukayo Saka to follow suit, with the defender's existing deal set to expire in 2024.

Sources told ESPN in January that there is a willingness on all sides to find a fresh agreement, but the club's latest offer had been rejected due in part to a significant gap between Saliba's wage demands and the club's offer. The sheer scale of Saliba's improvement is palpably a factor here, given he earns around £40,000 a week currently.

Although the precise terms of Saka's deal are yet to be publicly confirmed, he is reported to be about to sign an agreement worth £200,000 a week, more than double his previous wage. Meanwhile, Martinelli more than doubled his £70,000-a-week salary when agreeing his new deal. Saliba is entitled to demand a huge hike of his own, commensurate with those around him and his rapidly-growing reputation in the game.

Of course, his consistency at this level is yet to be proven and there are clear areas for further improvement. Brentford's Ivan Toney was able to dominate him in last month's 1-1 draw at Emirates Stadium to the extent that Pep Guardiola instructed his Manchester City side to play more direct when they travelled to the same venue five days later. Erling Haaland also gave Saliba a difficult 90 minutes as City won 3-1 to reignite their own title challenge and it is a tactic other opponents may well look to emulate before the season is out.

However, any continuation of the progress made to this point would see Saliba establish himself as one the most coveted defenders in the game. Far from when the youngster divided opinion, signing the defender to a new deal is now considered the next major milestone in Arsenal cementing their position as title challengers for years to come.