-Talbot apparently turned down an extension with the Ottawa Senators. He will be traded.
-This isn't really a 3-way trade, this is two subsequent trades that are linked together.
-Vegas and the 3rd are placeholders. It really doesn't matter where Talbot goes, and for what. 2nd, 3rd, 4th, 5th, etc. It's just meant to show that Ottawa would trade Talbot along with making this deal for Driedger.

-Joseph has not been very good in Ottawa.
-Driedger has no place in Seattle with their deep goalie pool. He is coming off of an injury, and his level of play will be questionable.
-Driedger has a worse contract than Joseph next year 3.5M cap hit and 4.5M salary vs 2.95M cap hit and 2.7M salary.
-Joseph has the worse contract long term, with 3 years remaining vs 1 year.
-Joseph is the better player right now, and Driedger is still very much an unknown quantity.

The Senators need a goalie signed for next year. Getting out of Joseph's contract justifies the risk that comes with acquiring Driedger, because the net gain in cap is only 550k and the net gain in salary is only 1.55M. Forsberg should be back for next year, but there is no guarantee that he will be able to play at a high level after nerfing both knees at once. They need an insurance policy. Driedger is waiver exempt, so if he fails to get back into the groove, they can send him down to the AHL. They will know by the end of the season if he is a fit. If he is not a fit, they would have the option to buy him out, and it would still be a net positive vs keeping the Joseph contract.

The Senators would need to acquire a PKer in a different trade to fill out their lineup.

I suspect the Senators may have to throw in an additional asset due to the term of Joseph.