Hard to say really.....he was 19 when he scored 120, not 20. Not many players are at their peak at 19......and he really wasn't either, problem is his injuries hit right when you'd expect him to be at his peak.
When he was 23-25 years old going through his injuries, he was dwarfing the competition in terms of PPG, basically pacing at 130-140pts over a full season. And that's in lower scoring years than his 120 as 19....the years he was doing that scoring was down 13-14%. HUGE DISCLAIMER - of course that is PPG and pace, you can't really go to far with that and could he have kept it up the full year....who knows.
He scored 94pts this year though, with a lethal power play rather than the worst in the league (which he needs to share some of the blame of course)...he most certainly would have scored more.......120pts is a bit of stretch though.