Heiskanen not on the same tier as those guys? Why not? He just had an incredible playoff run where only Hedman outplayed him when it comes to dmen...
He has been very far off when it comes to regular season point production. Makar has a 0.88 PPG in the NHL, Hughes a 0.78 and Dahlin a 0.60 ( 0.68 last season while becoming the second highest scoring teenage defenceman ever). Heiskanen has a ppg of 0.45 in the NHL, 0,51 last season.
Lets compare some defensive and two way stats, with the team rank since these stats are almost irrelevant otherwise, since they are heavily influenced by team puck possession.
Relative CF%
Hughes 6.0, team rank 4
Dahlin 3.6, team rank 4
Makar 2.6, team rank 7
Heiskanen 2.5, team rank 10
Relative FF%
Dahlin 1.5, team rank 8
Makar 2.5, team rank 10
Heiskanen 2.0, team rank 10
Hughes 5.5, team rank 5
Blocks : Heiskanen 84, Dahlin 51, Hughes 46, Makar 47.
Hits: Heiskanen 40, Dahlin 72, Makar 45, Hughes 7
Takeaways/giveaways: Heiskanen - 37, Dahlin - 26, Hughes - 25, Makar -6.
What picture does these stats paint? There is not much to separate them defensively, based on this. Makar is probably slightly worse than the rest in his own zone, but defensive ability is generally not really something you can base on stats. Offensively though, there clearly is a substantial difference.