Great signing for both the team and the player. Defensemen often take longer to develop so as a 23-year-old former 1st round draft pick he may still have some upside. I'm not sure how much chance he'll have to show it with Seattle's deep defence, but if he doesn't stick this contract should be easy to trade.
He's trending in the wrong direction, but the the past two seasons are strange enough to ignore and hope for a bounce back. Also, it is incredibly low risk. Incredibly low risk.