It's that age old question that gets debated over defencemen. Is being a really good offensive defenceman actually being good defensively? I'd argue it's not the same thing. But i can understand the argument the other way i guess.
I think there's an issue where people conflate skill sets with actual on-ice impact.
I would think that one of the best defencemen in the league at zone exits and zone entries would have a positive impact on team defence.
This article speaks a little bit to what puck possession can do from a defensive point of view, back from EK's run in 2017:
Consider the shot differentials with the Bergeron line and Karlsson both on and off of the ice. You can see the clear divide I’m talking about in both instances:
From a pure territorial advantage, both units are picking apart the opposition (note: scoring chances are strikingly similar from a percentage basis). But the disparity on the Karlsson side is the clear takeaway here. Boston is getting absolutely caved in whenever he’s on the ice, and that’s close to half of the game (he’s averaging close to 28 minutes a night). That puts an incredible amount of pressure on the Bruins to try to win the minutes he’s not out there. If the goals aren’t coming – and they aren’t right now for Boston – you’re in a bad spot.
A lot has been made about Karlsson’s scoring (he already has five assists in the series, a few of which have been of the highlight-reel variety), but the real hallmark of this series is in the data above. Boston simply can’t sustain offensive zone pressure when he’s out there. If they lose the puck, he recovers it and instantly breaks out – something the rest of the Ottawa defensive corps struggles with. Far too frequently he takes a high-pressure situation in the defensive zone and turns it into offensive zone time.
The ice is tilting toward Ottawa every time the Senators captain comes over the boards in the first-round series, Travis Yost writes.
www.tsn.ca
A lot of the "defensive skills" have to do with not having the puck on your stick - positioning, gap control, physicality, separation of man from the puck, blocking shots, etc.
However, you're in a vulnerable position in that case - unlike say a Mark Stone who has stolen possession in the offensive zone and kept the puck as far away from his own net as possible.
Anton Volchenkov was a legend when it came to blocking shots (he blocked 12 against the Capitals back in 2011 and was first star, including 5 of Alexander Ovechkin), but it also meant that he was passive in his own zone in a lot of cases, and a blocked shot doesn't necessarily mean a turnover.
Obviously the most well-rounded players and best defencemen have that broad skill set that encompasses both puck skills and play without the puck.
But that doesn't necessarily mean that they will have a greater on-ice impact than a specialist.
For this particular poll, I can’t think of anything Stone does better than Marner sufficiently to offset Marner’s overal offensive advantage. Marner is quite adept at takeaways himself.