Something that I've always been curious about is how much man-on-man or attack dog defense relative to more cerebral play was valued back in the day vs. how much it is now, or even how much the structure has changed for something like that. Like reading the description of Gainey, he seemed like a very straight-lined, singular focus player. I've read things about him like he shadowed the top wingers, but I don't know how that makes much sense when you're a winger in coverage in the defensive zone, unless it was so disorganized that they didn't play with even basic D-zone coverage.
Some people raise their arms up about the center "bias" for Selke voting now, but there's just so much more heavy lifting for a center relative to a wing, and you need to be so much more defensively conscious to play it effectively. A massive part of a center's job is to provide support to his teammates, especially in the D-zone. Looking back at Selke voting, it was so common to have wingers up there, I just wonder how much of it was for more of those splash plays, or for that "shadowing" aspect with some of the centers (or I guess wingers too, if some of them did it).
I think you see a lot of that in all sports when you have more limited footage or numbers; there's always a big emphasis on man-on-man defending compared to zone. I remember Nnamdi Asomugha in the NFL was the consensus best CB for a while, because he'd always go head-to-head against the best WR and essentially never give them anything. You can see his value in that, but when you look at overall impact he's not giving you anything else. It's a very singular focus, and he wasn't even trying to bait QBs into throwing his way, it was just a very simple strategy. He did his very specific job almost flawlessly, but how much did it really help the Raiders D overall? He signed in Philly where they had him play more zone and got shredded.
In hockey it's a bit different than something like football. Like in football there's still definitive value in a CB locking down a top WR. With hockey I don't see that as being as realistic of a strategy if you're so singularly focused.