Granlund has become something of a Swiss Army Knife player, moving up and down the lineup, playing center and wing, doing duty on both PP and PK, and generally attending to whatever chores the coach wants of him.
Unfortunately he's a small Swiss Army Knife with a limited selection of rather feeble blades. He's not particularly fast or dynamic, he's reasonably weak on the puck and plays a passive game, he has a good shot but lacks the shiftiness to make room for himself, and he tends to evaporate in games when either the physicality or pace escalates. His biggest attribute is his hockey IQ...he's a reasonably cerebral player. Probably why he's so adaptable.
A useful player, but he's never going to endear himself to fans, and will always be something of an afterthought. Given how erratic Kassian is it's probably an even trade without the 5th, but Kassian has about 300 times the X-Factor that Granlund has, and thus likely remains the more desirable asset.