You can be dumb as a box of rocks and still be a smart hockey player.
Day, unfortunately, just comes across as a guy with limited upside. He doesn't make very good reads defensively. He gets caught watching the play most of the time, and this is in juniors.
The one thing he does really well is skating the puck up the ice. He's a lot like Skjei in that regard. He can move the puck up the ice, but he's not a very good playmaker. If you took away everything else that makes Skjei a good, young D and just left him with his ability to skate the puck, is that player NHL level? Probably not.
Now, Day has been bounced around from coach to coach during his time in juniors, so I still have hope that it clicks for him. But, if I'm being honest, his ceiling is John Moore at this point. John Moore eventually figured out how to be a bottom pair staple in the NHL, but it took him over 5 years and 4 organizations to do so. The likelihood of Day panning out for us is very, very low, IMO.
But, we're in a completely different place now than when he was drafted, when it comes to LHD depth. And honestly, the expectations were never fair to him. He was our first pick in the 2016 draft, but it's not his fault we didn't have a 1st or 2nd rounder. He's about where you'd expect a 3rd rounder to be two years after the fact: good player in juniors with still a ton of questions about how his game will translate to the pros.