Kalvin Phillips is perhaps the finest individual success story of Marcelo Bielsa's time at Leeds United.
When the Argentine arrived, Phillips was a middling, box-to-box Championship midfielder. No Premier League club had designs on Leeds' No. 23 at that stage.
Bielsa identified specific characteristics in Phillips' game, issuing him with a summer task to re-learn everything he knew about himself as a professional footballer.
Phillips is now a fully-fledged England international, integral to Gareth Southgate's side, and the undoubted lynchpin of Leeds United throughout the Marcelo Bielsa era.
In true Bielsa fashion, the high point of Phillips' professional career was snatched away in the final of a major competition, but his impish grin and boyish demeanour won over the hearts and minds of a nation, as England truly began to understand his importance to Leeds United.
This season, without Phillips for over 50% of the campaign, Leeds have struggled immensely.
Combined with the absence of club captain and chief defensive organiser Liam Cooper, as well as last season's 17-goal striker Patrick Bamford, Leeds have been gutted of their spine and the protagonists of the 2019/20 promotion season.
Phillips, Cooper and Bamford all suffered hamstring injuries in the 2-2 draw with Brentford on December 5, 2021.
While Bamford recovered from that particular injury, only to sustain a further foot issue which he is currently battling to overcome, Phillips and Cooper are yet to return.
Since December 5, Leeds have conceded 40 goals in all competitions, across just 12 matches.
The Whites have conceded 20 in their last five, alone.
Leeds' record without Phillips in particular is an especially stark one.
This season, Phillips has missed 14 Premier League matches, and started 12.
Leeds have won just twice in 14 outings without him, winning three of their 12 with him in the side.
The crucial difference, though, is the number of heavy defeats the Whites have sustained when Phillips has been absent.
In the 12 games Phillips has played, Leeds lost just three times - to Liverpool, West Ham United and Tottenham Hotspur; the other six were drawn.
On the other hand, the Whites have lost 10 of 14 when Phillips has been unavailable this season.
It is a trend which has been apparent throughout Bielsa's tenure. Last season, Leeds lost seven out of nine league matches when Phillips did not play.
During the promotion campaign, a mid-season wobble which saw Leeds lose to nil against Wigan Athletic and Nottingham Forest in consecutive matches coincided with a three-game suspension Phillips was serving at the time.
While, in Bielsa's first season, Phillips missed just four league games - Leeds losing three of them.
It is an issue the 66-year-old has been unable to resolve throughout his time at Elland Road, and one which has contributed to situation the club has currently found itself in: considering the head coach's future.
With the aforementioned statistics surrounding Phillips' availability, it is not difficult to see the link between Leeds' current demise, the England international's three-month absence and word that Marcelo Bielsa is to be replaced.
