There is little doubt that Marcelo Bielsa was a big success at Leeds United for the majority of his time in the dugout with the Yorkshire-based outfit.
The former Marseille boss arrived at Elland Road with the club in the Championship and led them to a second-tier title and a ninth-placed Premier League finish before being sacked during the following season.
His excellent coaching and management secured top-flight football for the Whites and kept them in the division for another season, which is why he deserves huge credit for his work at the club.
Rodrigo
£25.9m
Dan James
£25.1m
Jean-Kevin Augustin
£18.2m
Diego Llorente
£17.3m
Raphinha
£16.1m
However, the 68-year-old was not without his faults, and some of his work in the transfer market, alongside sporting director Victor Orta, was questionable throughout his tenure in England.
One signing, in particular, that has turned out to be a blunder by Bielsa is central defender Robin Koch, who has endured a rough time since his move to the club in 2020.
How much did Leeds pay for Koch?
The Whites reportedly agreed a £13m package with Bundesliga side Freiburg to sign the centre-back ahead of the 2020/21 campaign, following their promotion from the Championship.
Leeds also signed Diego Llorente from Real Sociedad that summer in a reported £18m deal, yet Koch turned out to be a worse option in comparison to the Spanish enforcer.
However, Bielsa had snapped the German gem up off the back of a solid season for Freiburg throughout the 2019/20 term with the right-footed defender having racked up 82 top-flight appearances prior to his move to England.
He completed 84% of his attempted passes and showcased his defensive strength with 2.5 tackles and interceptions per game to go along with a duel success rate of 60%, as per Sofascore.
Leeds may have been hoping that he would be able to replicate that form at Premier League level but that did not turn out to be the case as Koch went on to struggle in the top-flight of English football.
How well did Koch perform for Leeds?
The Germany international had a solid, albeit unspectacular, debut campaign in England where he made 3.2 tackles and interceptions per game and came out on top in 58% of his battles, whilst the ex-Freiburg star also completed 86% of his attempted passes, as per Sofascore.
These statistics suggest that Koch's performances were not a million miles away from the displays that he put on in the Bundesliga for his former club.
The 27-year-old then followed that up with a dismal 2021/22 campaign for the Yorkshire-based outfit. He averaged a Sofascore rating of 6.51 across 20 Premier League matches, which was the 24th-highest score within the squad.
Opposition players found it far too easy to get the better of him throughout the season as the centre-back lost 55% of his individual duels, demonstrating that the £13m signing was not a dominant force at the back for Bielsa, and later Jesse Marsch.
Alongside his less-than-impressive defending, Koch offered very little to the team in possession to start attacks. As per FBref, the German ranked within the bottom 1% of his positional Premier League peers for progressive carries per 90 that season.
The ex-Freiburg star, who also ranked within the bottom 21% for progressive passes per 90, rarely progressed the ball forward for Leeds and was one of the worst in the division when it came to playing forward.
Koch still started 36 of Leeds' 38 top-flight matches last season as the club were relegated from the league. Llorente, on the other hand, enjoyed an excellent first season with the Whites before his dip in form and was a better centre-back for Bielsa than the Germany international.
How did Llorente perform for Leeds?
Across 15 Premier League games during the 2020/21 campaign, the Spanish defender caught the eye with 3.6 tackles and interceptions per match and a duel success rate of 57%.
He had the joint-seventh highest-rated score within the squad as Llorente proved himself to be one of the top performers in their ninth-placed finish at the top level.
However, the ex-Real Sociedad star then went on to average Sofascore ratings of 6.84 and 6.67 over the following two Premier League seasons respectively. This shows that his form dipped year-on-year before his loan move to Roma in January of this year.
Llorente, who ranks within the top 37% of his positional peers for progressive carries per 90 among the Men's Big Five Leagues and European competitions over the last 365 days, was still able to register a higher rating, whilst offering more as a passer, than Koch in all three seasons.
Evidently, he was a far better capture for Bielsa and Orta, despite their relegation to the second tier just a few month ago.
How much is Koch worth now?
At the time of writing, Football Transfers rates the German centre-back's expected transfer value (xTV) at €6m (£5m), meaning that the Leeds defender's valuation has plummeted by £8m from the £13m deal the club agreed for him in 2020.
Bielsa made quite the blunder with his decision to sanction the addition of Koch, who is currently on loan with Eintracht Frankfurt, as he was a poor performer on the pitch for the Whites and his market value has dropped significantly during his time at Elland Road.
Leeds reporter Beren Cross once criticised him as being "not good enough" and the aforementioned statistics certainly back that up as the £13m flop was far away from being one of the team's top performers throughout his three Premier League seasons with the Whites.
The club may now be hoping that Koch is able to turn his fortunes around at Frankfurt and produce more consistent performances.
Such an eventuality could well cause his valuation to soar back up in order to provide Daniel Farke with a chance to cash in on his services next summer to recoup some money back on him. Irrespective of whether Leeds find themselves in the Premier League again next term, a permanent sever of ties seems the best option.