The Red Devils shot-stopper was in fine form as United claimed a 1-0 victory over their bitter local rivals Liverpool on Sunday thanks to Wayne Rooney’s 78th-minute goal at Anfield.
De Gea produced a number of impressive saves to deny the likes of Emre Can as Louis van Gaal’s men returned to winning ways with a battling victory on Merseyside.
The Spain international was heavily linked with a transfer away from United in the summer but the move fell through after the necessary paperwork was not submitted in time.
And Crooks believes that United have De Gea to thank as they continue their push for a top-four finish this season.
Crooks told BBC Sport: “He made two world-class saves from Emre Can and that was what galvanised United and proved the springboard to victory.
“The shot from Can on the edge of the box was travelling like a bullet and it took a very athletic De Gea at full stretch to pull off the save.
“It is still a mystery why Real Madrid failed to land the much sought-after Spanish keeper but, whatever it was, with De Gea in goal a top-four finish for United seems almost guaranteed.”
Sunday’s win left United in fifth place in the table and just two points behind fourth-placed Tottenham.
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