That is what happens when a teen actor peaks at 17 or 15. They no longer are invested in their characters and it becomes a chore all of a sudden. Take a good at Modern Family. Out of all teen actors that passed awkward phrases in later teens, River Phoenix, Fred Savage, and Jason Bateman were the only ones that achieved that obstacle. I am not sure how Finn will do after Stranger Things since he has so much on his plate: his band and other film projects on his lap. Either way, I wish him luck.