Walton, who joined the club in the summer for a fee which could rise to a club record �750,000 from QPR, has struggled to find consistency in the Argyle set-up.
"There's been too many times when Simon has had these one or two good performances and then he's hit the slippery slope," Sturrock added.
Walton had been linked in the media with a move to Crewe but Alex boss Gudjon Thordarson has said there is no truth in the rumours.
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