There's certainly something to be said for that variance. It really is hard to ignore that top scoring forwards tend to come from the first round, particularly those Top-5/10 picks. And there are plenty of examples of Top-pairing defencemen coming from other places on the other end of that.
There's a very good chance however, that whoever we get at #5 isn't going to be a real "franchise player". As illlustrated in the list MS posted, 5th pick forwards are far from a guaranteed star. You hope your pick flourishes and blows expectations out of the water, but pragmatically speaking based on the history...you're more likely talking about a Voracek, Wheeler, etc level player, as a realistic "upside" expectation. You're doing very well if you can get that (though those two examples ironically, never really contributed to their full potential for their drafting teams). Great players, top-line players...but not "face of the franchise" types. Anything short of that type of real homerun hit...and you're probably talking about more of a good Top-6 forward (more of a B.Schenn, Brassard, Ladd type - again, very nice pieces to have, but none of whom realized full potential with their drafting team).
At which point, a puck-moving Top-3D is very comparable, or even favourable in "upside" to a Top-6F for me. Especially in terms of how impossible it is becoming to acquire a young Top-3 defenceman in today's NHL. Teams just don't trade them - unless we're talking a Johansen-Jones swap for a bonafide young #1C, or a messy contract situation like Hamilton (still swapped for a strong 1st [projected Top-6F like Connor, Barzal, etc.] and a pair of 2nds in a
deep draft
and a $6M contract). Other than that...how many other quality young Top-3D even change hands? They're just not available.
Which is where for me, the draft and "BPA" is really more about "MVP" - Most Valuable Piece. Looking at a realistic range of expected outcomes for a prospect, and which prospect holds value most through that range of
realistic expected outcomes. And how hard or costly it is to acquire that type of player elsewise.
I think you also have to look at how teams are constructed these days in the draft-heavy cap era. Top-line and top-pairing mean a lot less these days than "duos" and the type of minutes. Which is where the "upside" of a player like Juolevi kind of surges. Good, well built teams don't just throw their 2 best defencemen together by default, or their 3 best forwards on a single "top line". Calling someone like Juolevi a "Top-3D" upside is essentially saying...he's a guy who is either the sidekick on an all-world calibre pairing beside a true #1D, part of a tag-team top-pairing with a pair of #2s, or an absolute anchor of a very good 2nd pairing that plays substantial defensive minutes.
I mean, just look at the sort of partners most #1D types play with most - It's a lot of guys who would otherwise be more like a #4 maybe even a #5 in a vacuum. McNabb/Muzzin, Methot, Spurgeon, old Campbell, old Markov, old Martin, etc., even Stralman, Bouwmeester are more like "#3" types in the classic sense. This is where depth and diversification is so important - and where that "true #1D" is so rare and important, in that they can carry a #4 type to lofty heights. And also where a guy like Juolevi projects can have huge "upside" - and a ton of qualities that make him a "safe" bet to become a Top-3D of some sort, whether he's on your "top pairing" or you get more out of a player like that anchoring a "second pairing". Basically...i think the #2/3 distinction is hugely arbitrary and situational. To me, a true #3 who can anchor a second pairing is really none too different and maybe even "more valuable" than a guy playing in the #2 hole, depending on the situation. It's essentially the same thing.
Which is where concern over the "upside" of calling Juolevi a "Top-3D" projection is pretty unfounded. If Juolevi pans out as a Top-3 defenceman, you've got a heck of a player on your hands...as high an upside as you could reasonable expect at pick #5.
I do completely understand where you're coming from with the talk of "variance" in where top defencemen come from in the draft, and it's a fair point. But at the same time, i think what you're suggesting is teetering along the edge of a dangerous line. To where you're starting to bring "drafting for position" into the equation in an almost inverted sense. The idea of avoiding a specific position in the 1st round as a sort of "opportunity cost" principle, lends itself toward a dangerous precipice of bypassing a "BPA" for a different position - because you think you can get that position later. Rest assured - most 2nd round picks don't turn into Norris caliber defencemen.
BPA is a lot more complicated than people like to portray i guess. For me, position is absolutely already factored in, along with type of player, the range of value on the type of player they project as. It's why i try to build a list with league+position groups first (ie. CHL Defencemen list). Then integrate them from there.
That said, for the record...i still have 4 forwards ahead of Juolevi. Matthews and Laine who i think project as potential franchise players who are by default the "#1 line" whoever they play with. And Dubois and Tkachuk, who i'd call bluechip Top-3 forwards. They're either going to play on a top line, or carry a second line.
But in principle, i don't have any real issue with Juolevi's upside. For me, he's a guy who projects as a Top-3D...where it's hard to see a lower end where he doesn't find a home as a quality Top-4D. He's got the smarts, the mobility, and a very good frame to work with, transitions the puck at a near-elite level, and has a huge amount of efficiency to his game that bodes very well for big minute potential at the next level. Lacking an "exceptional" tool perhaps, but the balance of overall traits is the type of Top-3 defenceman that you simply cannot find on the market. They are NOT available, and to even start a conversation on one...you're talking about trading a young Top-3 forward.