Mika and Kreider just love throwing the puck into open spaces hoping each other will find the pass. Its actually quite concerning right now 5 on5 how much they arent generating.
Kakko is an in zone possession player who needs two linemates who cycle well and drive the net. A lot of Mika and Kreids offense/chances come via the rush - which Kakko does not excel at.
Mika circles up high waiting for a turnover, or an open lane to let the slapper go and is worried about covering up on D, so he cheats high and doesnt get deep enough into the zone often enough to support player like Kakko.
If Kreids isn't straight lining to a dump in or rush into the zone he usually becomes static, floats and just watches too often if he's not on his game 100%. He'll pot goals but he falls into those habits often 5on5. Theres a lot of in and outs with that line, whoever is on the right side.
So Kakko does have a better partner in Cuylle because they stay close to each other on the walls and can play catch a little. Cuylle steal pucks and takes the body like a maniac and that disruption is the type of stuff that leads to Kakko jumping on loose pucks and possession. The problem is they need another shooter who can also skate with a purpose on that line and its not Bonino.
If its Chytil, great - but ideally in that 3rd line role you would want Trocheck there because he can not only shoot but carry the puck and make some moves, forecheck, win faceoffs like an animal and go to the net. I think he would fit that lines assignments the best. 3rd line checking/shutdown/possession metrics