Reading comprehension not your strong suite? I said several times that Pettersson is certainly more valuable to the Penguins in the short term and potentially the long term. The penguins are a better team with Pettersson than Sprong. Also, Sprong may very well bust. However, it is my opinion that it is not good asset management to trade a guy when his value is at an all-time low, giving up a potential scoring winger for a 4-6 limited offense D-Man. If I were a pens fan id rather see them send out a 2-4th round pick for a serviceable 4-6 Dman than a prospect with a lot of potential. Odds are, it is a non-issue and Sprong doesn't develop into a player worth missing much, but he could.
If Pettersson had been avialable for a 2-4th rd pick, I'm pretty sure Rutherford would have just done that instead of moving him for Sprong. But contrary to HF believe, not every player is available for a pick. Pure value only goes so far, but 'needs' come into play a lot more in the NHL then HF fans think. There's really no reason for Anaheim to move Pettersson for a 2nd/4th rd pick. He's playing for them in the NHL... why would they trade him for a pick at this point in time?
Also you seem to be really hung up on a "potential" scoring winger for a "4-6 limited offense blueliner". Brian Dumoulin is a limited offense blueliner who's never put up 20+ points in the NHL, and who if he does exceed that, it probably won't be by much. And in no way shape or form is he a 4-6D - and he's a very good comparable for what Pettersson might be able to do.
And what does your "opinion" say about selling an asset before his value goes even lower? At some point it's time to cut bait and bail. Not everyone's value will increase. I know Sprong has been playing well for you guys, but I'm extremely certain that few (if any) of you have watched many Pittsburgh games where he was playing like utter trash (and this isn't sour grapes since he was traded, many have said the same thing going back to last month and beyond).