SpeakingOfTheDevils
Devils Advocate
Sorry, but you can't include non-trade pieces in trades. This trade's in a vacuum. If 2 2nds was the return, they should have been able to do better.
If you choose to adopt that perspective, sure.
In reality, though, they needed to dump every dollar of Subban's contract to afford Duchene. They certainly could have gotten much better for Subban, but it would have involved salary going the other way, which would have made Duchene an impossibility. Because NJD was probably the only team that could absorb the full value of Subban's deal, no questions asked, NSH was backed into a corner. Zero leverage, but they didn't care, because trading Subban to New Jersey all but guaranteed Duchene.
Subban for Duchene may not have happened on paper, but it was 100% Poile's calculus here.