Yes, there is an adjustment period. I don't think anyone can deny that. And he's gone through two of them this year - 1. to the Pens, 2. from MJ to MS. So I get that and I don't believe it's unreasonable to expect struggles...
...to a point. Kessel is getting to that point of "Okay...adjustment forgiveness is starting to be over...you need to start producing like you are paid to produce". He needs to figure out what works best with the team and do that. What makes a player a great player is their ability to take their skill sets and make them work within the parameters of their linemates and team.
Kessel is reminding me a bit of Iginla during him time here. We all expected Iginla to be a driving force here and it was more "Hey, you guys got this. I'm gonna grab a comfy spot right over here and let you guys do your thing. Don't mind me I don't want to get in the way". I'm seeing the same out of Kessel. More "Okay, so I'm on Malkin's line, he's the best in the world, I'll just hang out in the background and help him out a bit".
We need Kessel to be a driving force. The one he is capable of being. He needs to be studying video of Geno and start getting a feel for what Geno likes to do so he can complement that at an all star level. He's not here to be a Kunitz, Dupuis, Neal, etc...he's here to be a major offensive component. So far he has not done that.