I generally agree that it's dangerous to trade a young D like Dobson when he's having a down season. However, if we're talking about a deal around Dobson for Pettersson:
Dobson is just 14 months younger than Pettersson. so it's virtually an even swap age-wise;
Everything we're saying about Dobson we can also say about Pettersson. A year ago both were virtually untouchable, then finished their seasons on a down note and it continued into this season. Last year VC fans either wouldn't consider trading Pettersson, or wanted both Barzal and Dobson back in a deal for him. So they're both down in value right now.
Both get criticized for being soft. But if a guy is going to be "soft", better a forward than a D. And VC fans used to praise Pettersson for being such a great two-way player in addition to putting up points, no?
The Isles know Dobson better than we do. Maybe there is a concern about his motor/passion? IDK. And they know Pettersson a bit via Horvat. Maybe they view this as an opportunity to get an elite talent?