I've watched a few of his games this year, though not all. In those, he's had his moments of flashing what he can do, being strong with the puck on his stick, taking a first quick step to the slot/net and separating from defenders in doing so, etc.
But plenty of other times he's looked a bit timid. I think it is taking him some time to adjust to the speed and size of the NHL game and its players. He quite obviously doesn't have the size and speed advantage put there that he does in juniors ... And I think it's showing a bit in terms of him being a little hesitant, over thinking, and ultimately trying to not make a mistake rather than affirmatively make a play on many shifts.
That said, I actually think he COULD play in the league this season if he was properly supported by the coaching staff and allowed to play his game and learn from his mistakes. That's not Ruff's way though, as evidenced now by him playing 4th line minutes and getting practically zero PP time. That is detrimental to Grigorenko -- he just isn't and will never be a grinder.
As a Sabres fan, I think it signals that he'll be heading back down.
14 Team H2H Dynasty League (14 keepers, 21-man roster, no farm)
G, A, PPP, SOG, BS, +/-, GAA, W, SV%