Two things are clear from this deal: 1) Garth Snow is already in full future-planning mode, and 2) James Wisniewski was not going to re-sign with the Isles given the chance.
The Canadiens have had trouble scoring goals. Their power play is a very respectable 12th, but they felt Wisniewski could add something they were missing.
For the Islanders, it's simple: Snow got a good offer. He acquired Wisniewski for a third-round pick in July; turning a pending UFA into a second-rounder and a conditional fifth-rounder in 2012 is a good deal, even if it breaks up the current squad.
Losing Wisniewski's $3-million salary may appear to send the Isles below the $43.4-million NHL salary-cap floor, but achievable performance bonuses by players on the current roster push the Isles overall cap number to above $45-million, so there's no concerns about that.