Sprong being traded doesn't magically mean his flaws are going to go away. I'm not saying this to bash Sprong, I'm being reasonable about the problems he has as a player. Nothing I said was false or intended as sour grapes at Sprong, it's just a fact. He's an all-offense player that doesn't offer anything outside of his offense, so if he's not producing, he's going to be hurting your team.
It's why the comment that Sprong is a lot more likely to hit is potential is a reach, because Sprong has massive boom/bust potential unless he fixes the issues in his game. Pettersson doesn't have that boom/bust potential, the worst case scenario is a #5 defenseman.
No, but it was pretty obvious that how he was playing in PIT wasn't going to lead to a successful NHL career. In his first game with Anahiem (I haven't watched any of the others), he showed more of a pulse then he did in his last 6-8 Pens game combined.
Sprong when giving a shit and playing with a pulse is a useful prospect, and one who while maybe still a liability defensively, with questionable offense, at least attempts to contribute in other ways. We just never saw it. Good for him - because if he hadn't changed anything, he wasn't going to stay in the NHL. Hopefully he can keep progressing.