It's around what I expect. He just doesn't have the leverage to get much over 6. Not the track record, marquee status of being a top 3 pick and also isn't the 'face of the franchise', probably doesn't sell as many sweaters, is a winger, and hasn't been marketed as much as a lot of the other young stars.
Not all negotiations are created equal.
For arguments sake. He's as good as these other young stars - but those teams have to justify their brutal year to the STHers and market this high pick (Nugent-Hopkins for example) as a justification, giving the player a lot more leverage. Bruins never went through that. He'll sign around 6 for long term or around 4 as a bridge.
You're not wrong about some of that, but the issue here is Pastrnak really doesn't have any comparables also lacking the characteristics you mentioned...or any comparables at all.
In the last 10 years of draft picks, only 10 other players picked between #10 and #60 have scored 30 goals in any season (Pacioretty, Simmonds, Palmieri, Eberle, Tarasenko, Rakell, Jenner, Saad, Kucherov, and Forsberg). Out of those 10,
not a single one of them had scored 30 by their 3rd post-draft season...Eberle and Forsberg both needed 4, while everyone else was at least in their 22-year-old season or later. The point here being that Pastrnak largely compares more to a top-10 pick than anything else, which I'm sure is part of what his camp will be/is arguing...and honestly he compares favorably to a good majority of them as well.
This thread is filled with comparable player comparisons for him, but ultimately progression/ceiling-wise the closest tend to be top-10 guys like Seguin, Hall, RNH, Evander Kane, Tavares, etc. Even adding in someone like Eberle, the main thing they all have in common is they all signed long-term deals for between 8.5% and 10% of the cap. If you apply that same mentality to Pastrnak, he's realistically looking at a minimum AAV of $6.375M...and as I mentioned before, that's not even accounting for buying extra UFA years (most of those deals only bought 2).
Who knows, maybe they can talk him way down by bringing up that he's not our best winger or doesn't have marquee status or marketing ability like you mentioned. But if Sweeney does manage that, IMO it'll be a legendary signing, because everything points towards him getting way more.