The seven-time Pro Bowl selection praised the throwing motion, pocket presence and quarterback IQ of Rosen, who was selected by Arizona with the 10th overall pick of the 2018 NFL Draft.
Rosen initially caused a stir on draft night when he said "there were nine mistakes ahead of me," but Peterson said on "The Rich Eisen Show" that the rookie hasn't provided any distractions with the Cardinals.
"Honestly since he's been with us, he's been the total opposite of what you hear from the media or you hear from outside people," the 27-year-old Peterson said on "The Rich Eisen Show", via NFL.com. "The way he's able to grasp the offense and get guys in line right now, I've been very, very impressed with that. As far as his throwing motion and his quarterback IQ and his pocket presence and all that stuff, it's off the charts. I've never seen a rookie come on a team and do some of the things he's doing."
Peterson didn't stop there when speaking during an interview with Sirius XM NFL Radio.
"Josh blew my mind my first week with him," Peterson said. "Just to see him run hurry up offense, to see him make all these different checks, to see him put guys in position. I was completely stunned when I saw it. I was like, this guy's only been here for a week and he's already doing what? We're already running a two-minute offense now? I was very, very impressed with that. He's definitely the future of our franchise."
Despite the praise, Peterson said that Sam Bradford likely would be the team's starting quarterback this season.
Bradford signed a one-year, $20 million contract with the Cardinals in March.
The 30-year-old Bradford has a lengthy injury history, appearing in only two games with the Minnesota Vikings in 2017. He has played 80 of a possible 112 regular-season games. If he can stay on the field, the former Heisman Trophy winner and No. 1 overall pick in 2010 is expected to be under center in Week 1.
Rosen passed for 3,754 yards and 26 touchdowns with 10 interceptions in 2017 with UCLA. He posted career numbers of 9,301 yards passing with 59 touchdowns and 26 interceptions in 30 games.