Franck Passi has accused Marcelo Bielsa of having grey areas in his managerial style.
The 54-year-old has worked closely with the Leeds United boss before, serving as his assistant at Marseille before also being appointed caretaker manager at Lille ahead of Bielsa's ill-fated stint there in 2017.
Having also spent time as Bielsa's translator at Marseille, Passi knows the 65-year-old well.
In an appearance on Telefoot Chaine on Monday, Passi was asked who the real Bielsa was. The one that was loved at Marseille, or hated at Lille.
Passi pointed to Bielsa's good work at Elland Road in his answer, but explained it is never clear-cut with the Argentine.
He said: “I think it’s a bit of both.
"Marcelo, what he did at Marseille and what he’s doing at Leeds, it’s very remarkable, but if there was that hiccup at Lille, where I spent time, there has to be some grey areas."
Bielsa's spell at Lille, his last managerial job before he took over at the Whites, is infamous.
While it was not quite as short as his 2016 stint at Lazio, which lasted just two days due to issues over recruiting players, he took charge of just 13 games at Lille.
Bielsa signed a two-year contract at the French club in the summer of 2017, but took just 12 points from their opening 13 matches before being suspended in mid-November and officially departing a month later.
Bielsa was given a free rein at Lille, which saw him jettison experienced players in exchange for young talents.
It led to Lille sporting director Luis Campos claiming Bielsa wielded too much power and got rid of too many players.
He said to RMC in February 2018: "We have to accept that we made mistakes. We have to say that clearly.
"The first is when the club practically gave the keys to the former coach so that he can build his own sporting project.
"There came a time when the club decided to give practically all the power to the former coach and in my opinion that moment is going to weigh heavily on the whole season.
"We're going to pay very dearly for that the whole season long."
He added: "You cannot build a team without having a spine of experienced players to support quality youngsters.
"For me, that was when the project was broken."
Yet, with the likes of Nicolas Pepe, Kevin Malcuit and Thiago Mendes all going onto better things, it could be argued Bielsa's judgement over some of the younger players he chose to blood have eventually been proven correct in the long run.
