I would argue one reason Granlund is less turnover prone than Fiala would be he seems to have puck possession at a lesser rate. I also see Granlund hold the puck and try to dangle around people to lose possession, which seemed to infuriate our fan base when Fiala did it. Fiala was our best zone entry forward and had the puck on his stick often for entry and exits. I didn't love the trade at the time, and I have seen nothing from Granlund that makes me think we have won this deal. If we only get 1 year out of Granlund as a slightly better version of Fiala and then he asks for 8+ million per year then it's a clear loss in my mind.
I would still say to this point, Boyle is the only trade that you make if you know what you know now. Sure, you can say 'give it some time', but based purely on RIGHT NOW then you don't make the Simmonds deal or the Granlund move.
Now, I do agree that Granlund is suffering from poor line play. It's possible we still love this deal next year if we can make something happen to upgrade Turris (a la Duchene). Better yet, something may change with Turris this year and we could absolutely be loving this trade and the Simmonds deal on a long playoff run. Things change, but I am only judging things on this short 8 game window.