From watching him here in BC, Edler's play has regressed since the playoffs two years ago. I don't know if it's just a confidence issue but he's really not playing to his $5M per season long term deal.
As to why the Canucks are looking at doing this, it's because they have too many defensemen and they need to shed some salary for next year.
1. Tinordi meets a need for our team, while Edler is a nice addition to a blue line that is already good at moving the puck.
2. The salaries of Moen and Desharnais aren't enough to make up the gap between the perceived value of Tinordi and Edler. Also Desharnais is a good player, despite the contract.
Not suggesting they go move Tinordi. But if that's what Vancouver wanted, sure. Edler's world class and signed throughout the rest of his prime. I'd take my chances with a defence of Subban, Edler, Markov, Emelin, Gorges, Diaz the next two seasons.
Vancouver would probably ask for JT. It would be tough, Tinordi can fill a big role on the Habs D. Would rather move Beaulieu or Diaz.