I could bet 50 euros for Haula ending up better in the NHL than Granlund. Granlund has been avoiding the goal scoring zones after the numerous concussions and he is still a lot slower than Haula. Just prediction
Unfortunately, I think Haula has had concussion problems also. I worry about both players having shortened careers.
A very quick perusal of TOI shows that Haula has 570 min, Granlund 1054. Of those, Haula is going to have more PK time, Granlund PP time. Haula has 34% O zone starts, Granlund in the 50's.
You can make stats say say just about anything. Granlund probably has faced tougher competition... But then, he's been playing with better, usually FAR better, if you include PP, linemates.
I do think that Haula is a better defensive player already. Comparing them offensively is kind of pointless right now. They have completely different roles on the team. If Haula can get Poms going somehow( which I doubt), then he deserves a medal.
It will be a nice problem for the team if there is a debate over who is better. That will mean that Haula is playing his ass off.