Barker, now assistant boss to Warne at the Millers, knows Potter well from their time together at MK Dons.
The Rotherham No 2 is notoriously hard to please, so his glowing recommendation of the 32-year-old, who has signed a two-year contract at New York Stadium, sealed the deal for Warne.
“When I spoke to Richie about him, he said Potts is one of the best pros he’s ever worked with,” the manager revealed. “You can’t get a better commendation than that because Richie sees the bad in everyone!
“I want someone who can control the pace of the play and someone who will allow the front five or six to really attack. He’s the perfect fit for me.”
More arrivals are expected at New York in the next few days, with midfielder Ryan Williams and striker David Ball thought to be close to joining the Millers.
Potter, who started his career at home-town club Liverpool FC, has spent virtually all of his career in the Championship or League One and is seen as a key capture by the Millers who are planning for life in League One following their relegation last season.
“He’s an experienced pro who’s played loads of games and he’s a really good character,” Warne added.
“I think he’ll be a good, stable part of the team. I want pace and power, but I also need a bit of football guile, and that is definitely what he brings.
“He’s been involved in promotions. If you look at his playing record over the years, it’s hugely impressive.”
Potter admitted Barker’s presence in South Yorkshire was a factor in him moving north after six years at Stadium MK.
“Richie was a big influence and I’ve made no bones about that,” he said. “We worked together at MK for two and a half seasons. He told me a lot about the club and the manager here and that it would probably be a good step for me to take next.
“Obviously, there is going to be a lot of change, with Richie coming in and being part of the staff.
“Maybe, after the last season, players will be leaving with new players coming in. I think it will be an exciting challenge.”