I tend to put stock in Bob's rankings, because 1) They carry real NHL weight, 2) They carry the opinions of those who are much smarter than myself, and and 3) They have at least somewhat of a sample size beyond one dude.
First off, let me say I actually like the others better than Smith myself, personally. I predict Carlsson and Michkov both end up having better NHL careers when we look back 15/20 years from now.
But, I think it's safe to assume Smith has 'played his way up' into that #3 ranking, which is great news. At least according to NHL level scouts, he has raised his game. It's not like any of the others in that tier played down and got passed; if anything I'm surprised there's not more positive attention/stock rising on Carlsson given his recent play.
Now we can kind of treat it like it's not a 2-4 tier, but it's a 2-5 tier we will likely draft in. This gives us insurance and means we can get a reasonably equally valued prospect in that tier without having to draft a riskier picks. And who knows, we could even see Carlsson at 4, like others have said.