Sure Tanev is better defensively but is a lesser player offensively and physically. Edler still a better overall player.
Hutton is basically the opposite of Tanev. Edler is again, a better overall player (so far anyway).
Never mind that none of those guys play the same role on D and aren't truly comparable (Edler, top 2, 2 way D with some offense and physicality, Tanev top 4 shutdown PMD, Hutton top 4 offensive D). You're apples and oranging.
I never said anything about Gudbranson, not sure why you'd bring him up? And for the record I was on board with Gudbranson before we even made the trade. Even made some trade proposals for him. Was thrilled when Benning got him for far less than I thought he'd cost. None of that has a thing to do with Edler.
His play really hasn't slipped much if at all. Sure there's probably a touch of age related decline but the only thing that's really changed is the team around him. The quality of his D partner, the rest of the top 4 (even 6) D and the quality and depth of forwards. It's very similar to the Sedins 'decline'. Give them a D core with a legit top pair, offensive PMD and secondary scoring/forward depth like we had from 2010-2012 and they'd likely be a lot closer to PPG players than they are now. Edler would likely be ~35+ point D again and our PP would not have looked so horrid the last few years.
People discount far too much just how good our team was those few years and how greatly the comparative lack of depth and quality has affected the remaining players performance. It's a TEAM sport. Our team has not been very good.