Van de Beek has failed to establish himself as a regular in Ole Gunnar Solskjaer’s team since arriving in the summer of 2020.
The Dutchman was handed a rare start for the visit of the Hammers, but failed to impress yet again as United crashed out of the competition.
Manuel Lanzini’s goal in the ninth minute proved to the winner at Old Trafford.
When analysing the only goal of the game, Stoney said on Sky Sports: “It’s poor defending, he (van de Beek) has got him in his eyesight. I don’t know why he thinks he’s got to go after the ball, he just needs to stay with his player.
“He’s been drawn to the ball, he’s had his eyes on the ball, not checked his shoulder, there’s only one ball from the by-line and that’s the cut-back, that’s the danger so you’ve got to stay on your player and realise the danger.”
