The Republic of Ireland goalkeeper moved to Manchester City from Newcastle United after spending 12 years with the Magpies, but the 35-year-old fell behind England No1 Joe Hart under Roberto Mancini at Eastlands.
A lack of regular first-team football prompted Villa to snap him up for a cut-price £3.5m in July, which left-back Warnock believes is exceptional value for an international goalkeeper.
“Shay is fantastic. Everyone knows his ability but he had been out of the game for a year. However, we always knew with his hunger coming back into a team and wanting to be the best, he’d thrive at Villa,” Warnock told Villa’s website.
“It’s the pride of a footballer to come back and show how good he is and prove people wrong.
“That’s one of the things about football. If your face fits that’s great. Shay’s face didn’t fit at Manchester City at the time but he’s come here and his face fits and we’re reaping the rewards of a great buy in the summer.
“He’s a great character to have around the changing room aswell. The lads love him. He’s always bubbly and he’s never afraid to tell people how it is either, which is always good.
“He has great experience and you can never knock that. He’s one of the best buys of the summer, no question. In fact if we’d paid a bit more money, I would still say he was one of the best buys of the season.
“A lot of clubs probably looked at him but thought about his age but I think you’ll see that he’s similar to Brad.
“He’s going to play into his 40s in my opinion and he looks as young now as he did a few years ago. He looks after himself, he’s a great pro and he’s reaping the rewards of looking after himself.”
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