Speaking on TalkSPORT, the ex-Sunderland man believes Steve Bruce has got a bargain, after the 30-year-old penned a one-year, deadline day deal.
And McCoist has even drawn comparisons with one of his former teammates – another injury-hit striker with a bolt of left foot, and a beast in the air.
“When he is fully fit he is one of the most exciting strikers, like a Duncan Ferguson was,” said McCoist.
“He is almost unplayable, physical, strong, scores wonderful goals.
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“I just hope he gets fit and stays fit - what an exciting player for the fans.”
On Carroll’s move back ‘home’ after eight years away, McCoist continued: “I love that.
“I like that he's away back to the Toon. If they can get him fit it is a real boost.”