It’s justifiable to trade away high draft picks and prospects when you have a legitimate chance at winning a Cup.
But when you have an old and flawed team that will be doing well to just squeak into the playoffs, the last thing you should be doing is trading away high draft picks and prospects for a 33yr old defenceman who’s not very good defensively and has four years left on an $11.5M boat anchor.
Horribly misguided trade.
Going to play Devil's advocate here, as my favorite team (Hawks) did the same thing to a lesser extent with Seth Jones. And both organizations have had those deals (and subsequent contracts in SJ's case) - not going the way they would have liked.
You have an organization that has had unreal bounty of success over the last 10-15 years winning 3 Cups. Some of the real "core" of those teams is still around and really darn good, but now in their mid-30's aren't as dominant as they were in their prime. The organization looks at it, and understands how RARE it is to be in this position, and even if it is a long shot, they want to see if there is one more run potentially. They know that the run is unlikely - but when is going to be the next time that you have multiple future HOF'ers still playing at a high level? (Less so for the Hawks here). At that point - they make a "dangerous" trade to bring in a missing piece of what they think is a legit #1 d-man. I think that if Dubas answered truthfully he would have said the Karlsson deal works maybe 25% of the time - but that deal was the best chance for the Pens who hadn't won a play-off series in 5 years.
I look at this similarly to what Treliving has done with the "Core 4" in TOR. He knows how rare it is to have a top 3 players group as good as AM/MM/WN, so he's paying them whatever it takes to lock them up, and then trying to figure out how to build the rest of the team around that. It's probably not the way he'd prefer to go, but those are the cards he's dealt and you have to try to win with what you've got - not what you wish you had.