McGinn, who has not played since injuring his ankle in December, is set to be involved in Wednesday night's clash with Sheffield United.
“They have certainly missed him," Sherwood told talkSPORT.
“He gets on with doing the ugly stuff in the game, gets round, puts his foot in, gives the ball to Grealish, who they know is the jewel in the crown.
“They are so reliant, I don't know any team for a very long time that is so reliant on one player.
“Give him the ball in the last few minutes of the game, he takes it to the heart of the defence, he causes havoc – he could be their reason.
“I am certain if they stay up Jack Grealish is the reason."
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