I wouldn't say the value is off, but as others have already said it'd be pretty tough for Nashville to swing that deal right now. We could very much use Boeser. But at the same time, our D is too thin too so we can't afford to lose Fabbro without replacing him. And we only have about $5M in cap space as it is.
If there was some way to do this and KNOW that we could sign a couple solid UFA D, then it might be a different story. But we won't have the cap space left to do it. So we can't take this option. If we want a new winger, we'll have to make do with some kind of temporary bargain UFA patch instead of trading for a better player like Boeser.