The seven-time World Champion fell and hit his head on a rock while skiing with his son at Meribel on Sunday morning.
He was then airlifted to the University Hospital of Grenoble where he underwent a neurosurgical intervention and was placed in a medically induced coma.
"We know that the accident took place in an off-piste zone where rocks were partly or totally hidden by snow. Schumacher had likely been thrown off balance by one of them," Quincy told Reuters on Monday.
Following the accident, Schumacher's manager Sabine Kehm admitted that his family is under severe stress following the accident, but dismissed suggestions that the 44-year-old took on one too many risk on the Meribel slopes.
"The family is not doing very well, obviously," Kehm said.
"It was not an off-piste track. They (Schumacher and his son Mick) were skiing on pistes, but in the moment that it happened, it was not on the piste."