crusingthroughreality:

Jeff Davis: And now there’s the mention of Greenberg. And I remember you coming up to me and saying ‘which one is Greenberg?’ And me saying ‘that’s the point, there is no Greenberg.’
Toby Wilkins: Greenberg is an unseen character.
Jeff Davis: And may actually be a figment of Coach’s imagination.

Heart Monitor behind the scenes commentary

Greenberg is the way Coach takes out all the aggression he can’t take out on the real kids.

Imagine the first time he talked about Greenberg. All the guys in the team would look around and whisper to each other “who the hell is Greenberg” and coach would hear people talk and just say “Shut up Greenberg”.

And Stiles would be like “yep, that’s it, he finally snapped and we’re all going to die”.