Smoak is a half-decent 1B or DH and they have enough money to sign Napoli or Morales for the other. Seems like they can sign a second-tier outfielder too, maybe Corey Hart. Then if they acquire Price or another top starter with Walker, their rotation will be really good. I think that team would have a shot at the playoffs.
The Mariners didn't have a whole lot of hope in 2015+, so why spend another year in mediocrity for nothing? They'd only continue to fall behind the A's and Rangers, and soon the Astros would be on them. Winning games is the goal of any MLB franchise, and Cano will win the Mariners a lot of games. Maybe they'll lose the $/WAR Olympics, but they do have a lot of payroll flexibility and have had a difficult time recently getting players to take their money. They needed something big to happen this offseason. Cano qualified as that and they could afford it, so they pulled the trigger. I like this move a lot.