Fans of the NHL draft often speak as if there is a lot of consensus about who is likely to go where in the draft. They might follow the ISS lists that come out every month, not see a lot of movement, and think that this means consensus is building. That notion needs to be dispelled.
First, we only see the lists of scouting services, not of the teams. So we only see a small portion of the qualified lists out there. Second, it's only the very top guys which scouts can agree on, and here we're only talking say top three. Beyond that, as you move away from the top, there is more and more variance, to the point where someone who is very high on one NHL team's list may not even appear on another's. Teams vary in their draft philosophy and tastes. There are 30 NHL teams, and that means 30 very different-looking lists. Teams usually only rank 125 guys per year. They did this even when there were nine rounds of the draft (290 taken) because no one likes the same guys and all 125 would never be taken.
First rounders regularly bust and guys who went undrafted regularly make the NHL. Thus it shouldn't be surprising that at age 17, opinions about these players should vary. But leading into the draft, when someone voices an opinion about a player that is seen to go against a perceived consensus, they are too often thought a fool. The Phoenix Coyotes took Blake Wheeler at fifth overall in 2004 and it raised a lot of eyebrows. It shouldn't have. The only thing they did wrong there was fail to take advantage of how little other teams valued Wheeler by trading down.
Back to the lists. There is usually a lot of change over the course of the season as well. Players who were good at age 15 and 16 often will plateau (Angelo Esposito), while the late-developers start to shine (Calvin de Haan). Seventeen-year-olds are only halfway developed. And at 17, players will develop just from the beginning of their draft year to the end. Late risers get taken high in every draft -- guys who are thought to have a lot of upside because they are still developing rapidly.
The Combine is a big factor in teams' rankings, with the battery of tests and interviews that it has. Peter Holland fell in the eyes of many, with the exception of Anaheim, after last year's. The playoffs are key too. And the playoffs for the junior leagues are still in the thick of things when the Central final list comes out. There's still lots more to go. Plus the U-18s, don't forget those. They can make or break someone.
All of this variance means that trying to do a mock draft before about April is pretty much ludicrous. You're much better served simply learning the players early in the year rather than trying to match them up with teams. NHL teams don't make their final list until early June just after the Combine. This is when mock drafts should be done.
Some people find scouting service Red Line Report to be "out there" -- believing they have far-out opinions. I don't think they are any farther out than an NHL team is. Some things they get right, some things they get wrong.
Personally I find my opinions closest to those of Central Scouting. I think they overvalue size a bit, but if I know that going in I can mentally correct for it. Their goalie rankings are decent. They had A. J. Thelen lower in 2004 than some others did, and turned out to be correct.
In sum, scouts are paid to have strong opinions about players. And they do. And they vary -- widely.
If we knew which 40 or so guys from each draft were going to make the NHL, we could stop at two rounds. But it goes seven rounds, because no one is sure where the next player will come from.