Gagner's strongest attribute is his creativity and his ability to make plays in the offensive zone. The biggest knock on him is his defensive game and his inability to play a physical game but if you give him space, he can be very effective. I can see Gagner being the same PP unit as Voracek and Giroux and make it very lethal. He can definitely be effective in that front.
He won't be on PP1 as he's not going to take Simmonds spot and he's the wrong handedness to play the spot in the middle of the ice that Schenn or Raffl played the majority of the year, but I think theres a strong possibility he lines up as G and Jakes LW at ES and runs our 2nd PP unit at G's spot this year.
We have also been historically bad at shootouts since their inception so hopefully he can help us there too.