In his rookie year, Scheifele had a good season, collecting 34 points, including 13 goals. It was after this campaign that the former 7th overall pick in 2011 really became an impact player in the NHL.
Also 21 years old, Habs center Jesperi Kotkaniemi has yet to establish himself as a top-6 center in the NHL. After scoring 34 points in his rookie season, Kotkaniemi's performance has declined over the following two seasons. However, it should be noted that the Finn entered the league at the age of 18.
With the departure of Phillip Danault, the Pori native will see his responsibilities increase next season. Playing full-time in the top-6, Kotkaniemi will certainly have to have a good campaign in his fourth year in the pros.
As a center, there is nothing alarming about him yet. Take center Sean Couturier for example. After having a good first season, he also slowed down afterwards. It wasn't until he was 22 years old that the Flyers player took off in Philadelphia.