Lets be fair here.
Day is a MUCH better skater than anyone.
Graves is a pretty good skater for a player his size, he's no less mobile than someone like Nick Holden, and we all know mobility is not Holden's problem.
I also think you are completely wrong about offensive instincts and vision. Graves has really good offensive instincts and vision. People paint him as just this guy who can shoot the puck. I get that he's good at that, but he has above average vision and instincts.
I think Graves and Day are pretty similar players. They are both more offensive than defensive players. Day has elite skating, Graves has an elite shot, although Graves is a good skater and Day has a good shot. They both are above average with puck moving, offensive instincts, playmaking. They both have excellent size also. The main difference is that Graves is what a few years of good development would look like for Day. Graves defense is still a work in progress, but its at a high enough level that it can not be exposed in the NHL, its pretty good for the AHL, just not great for the AHL yet. Day would be completely exposed defensively in the NHL, and might even be so in the AHL this season, so I think arguing that Day>Graves makes little sense, although given who you voted for, I'm not sure you are arguing that. Some definitely are though.