He is very perimeter in his play and if you take a really good start last season, he had like 11 pts in his last 30+ games, while being quite bad defensively. He is smallish as well, and I don't see good enough skating/skills that he will be really good. I think he will eventually be a 20-45 pt player that bounces around teams bottom sixes but isn't consistent at all. Kind of like an AA type. I definitely don't see a core piece with him.
Granted I want to be wrong, I 100% do, as who doesn't want him to be good, I just don't see anything great from him. I mentioned in another post that to me he is poor man's Tatar/Hudler/Nyquist type as all 3 of those guys could wow you at times, and I don't recall being wowed by Berggren with much.
As far as scoring in a bottom 6 role, you would need to bring something else, as chances to score are lower on the bottom lines, like for example Sprong isn't great in his own end, but he actually fore checks pretty aggressively while away from the puck Berggren for lack of a better word is just kind of skating around.