Lets break this down for you Mr. Economics.
Pastrnak was used as an example of fair market value for Nylander. After 1 season of 1st line production Pastrnak signed 6 years at 8.9% of the cap, after 2 seasons of 1st line production, albeit lower than Pastrnak, Nylander signed 6 years at 8.76%. Very comparable players and Nylander signed @ slightly less % of the cap. Both have since out performed their contract, Pastrnak by a larger margin.
Patrice Bergeron signed in 2013 (7 years ago) 8 years @ 10.69%. He was still a two-way beast at the time, but his offensive production was lower end 1st line and wasnt considered a top 10 C like he is today. Fortunately for Boston, Bergeron aged like fine wine. Tavares signed 7 years @ 13.8% of the cap as a UFA scoring over P/GP in 3 of his last 5 seasons and regarded as an elite 1C. Unfortunately offensive production is more valuable than two-way play in contract negotiations.
Brad Marchand signed in 2016 coming off his career year of 61 points (0.65 P/GP). The years leading up to his contract negotiations he was largely a 40-50 point 2nd line pest. He has since blew up and became one of the best offensive threats in the game, but even the biggest Bruins homer could not have predicted his massive leap in development at 28 years old.
Im not going to go over the Matthews deal because its hard to argue the negatives other than term. Marners I wont advocate for because I personally would have taken the 4 1sts, I do not like his at all and he shouldve been in the ~9.5 mill range.
As for those Bruins contracts that should have been an "example" well they look good because of a combination of a consistently raising cap (until this year) and players that improved performance AFTER signing their contract.
The lower roster guys have fine contracts so I dont understand what you are up in arms about.
You really think Lou would listen to Dubas advocating for anything? Lou is as stubborn as they come.