The PSG star was handed a first pro deal by Silvestre at Rennes, with the former Manchester United defender having to talk round the then 18 year-old after he had fallen out with the club's academy coaches at the time.
Silvestre had long likened Dembele to Cristiano Ronaldo and had seen the then teenager as a future world-beater.
Four years ago, Silvestre recalled to Tribalfootball.com: "Ousmane broke into the team very early into his career, I was there to witness his development and since then he's barely had a full season without injury.
"That's really where things have gone wrong for him because when he's on top form he's such a good player."
Silvestre also stated: "When I was comparing him to Cristiano it was, for me, a way of putting pressure on him in terms of demand.
"To reach that level, you have to be hard working. He is already -- he can still develop.
"Has he the ability to become a really great player? I say yes without hesitation. But it's the mindset that will make the difference."