This is his 4th NORF. Although he is having first season with R5 car. He did two seasons good times in Finnish Championship with old Mitsu evo9. Before that couple of seasons with Fiesta R2. He has much less rallying experience than Kalle Rovanperä for example.
btw. some guy called Ogier had his first JWRC season in age of 25. I'm not saying Pietarinen is the next Ogier, but for sure he has still a lot potential to unleash.