Alex Kovalev immediately came to mind even though he wasn't always PPG. That dude left at least 200-300 career points on the table just because he was so damn inconsistent despite the fact he had the talent for it.
HM to the not well known Nikolai Zherdev. He never came close to the same stratosphere of point production as Kovalev but that dude... you've got to be JOKING with as much talent as he had. All tools and no box. If he had ever managed to put it together mentally I have no doubt he could've been a very good one
Was looking to see if someone mentioned Kovalev before I replied. Kucherov is a Kovalev clone except I think Kucherov will actually apply himself