Duff believes the Belgium superstar should be blamed for his current woes at the Spanish capital.
Real Madrid paid a mammoth amount to secure the services of Hazard from Chelsea before the beginning of the 2019/2020 season, but the former Lille man is yet to impress in La Liga.
A series of poor performances and gnawing injuries in Spain is curtailing the talent of the Belgian.
Hazard has only played 38 matches in all competitions in two seasons for Los Blancos with the 30-year-old scoring only four goals.
Duff, who won two Premier League titles with the Blues, has questioned Hazard’s professionalism.
“You’d worry for him going forward,” Duff told RTE. “He’s 30, he relies on sharpness, being a quick dribbler. We all know after 30 it’s downhill.
“He’s never been a top pro and he’s never had the drive of (Lionel) Messi and (Cristiano) Ronaldo. If he did, you’d probably be mentioning him with them two players.
“He turned up for his first pre-season at Real Madrid – Galactico, €160million – overweight. Fat. Call it what you want.
“You’d worry for him, because he’s had 11 injuries and to come back from 11 injuries – and he’s hardly played in two years – you need to have drive, you need to be a top pro.
“You could argue that throughout his career, he’s always battled with his weight. To be signed by Real Madrid, €160million, you turn up to pre-season in the shape of your life.
“And he turned up overweight because he was on holiday. I am not having that. I hate aiming it at a player, but it’s always been aimed at him anyway.”
