After a three-match absence triggered by the removal of his wisdom teeth, the goalkeeper is looking for a recall when the Old Trafford Club host West Ham on Wednesday.
Despite reservations still existing over de Gea's ability to command his penalty area, the 22-year-old's agility is beyond question.
"I admire David," said Schmeichel. "I cannot remember anyone coming into United and being criticised the way he was.
"He was ridiculed every day. He was the subject of every debate in the media. Yet he still went out there with a smile on his face and managed to dig himself out of it.
"Very slowly he is working his way away from what people thought of him 18 months ago.
"He is young. At 22 he has things to learn but, mentally, there is definitely material there."