His last 3 seasons before signing the deal, MacKinnon was pacing for
41 goals, 110 points
34 goals, 111 points
40 goals, 111 points
For the last 3 years (including this one), Rantanen has paced
39 goals, 100 points
55 goals, 105 points
42 goals, 103 points
I'm not saying it's a drastic difference in production, but it's still a difference. And MacKinnon is a center, that commands more than a winger in this league.
He will get less than MacKinnon, at least on this team. If he wants more, he can sign elsewhere. To be honest, it's going to be hard enough to keep Mikko even if he will sign for a reasonable 12ish million.
In the end, both fantastic but Rantanen is the Drai to McJesus(in this case MacK).
Not the same. They work well together but one is still clearly the better player.