Scheifele = 8.39% (8 year deal)
Ehlers = 8.00% (7 year deal)
Larkin = 7.67% (5 year deal)
Forsberg = 8.22% (6 year deal)
Nylander = 8.77% (6 year deal)
Pastrnak = 8.89% (6 year deal)
Pastrnak when he signed was coming off a 70 point / 34 goal season in 75 games at age 20. Nylander was coming off a 61 point 20 goal season at age 21. So he was worse at an older age where he should have been further along in his development yet deserved the same money? His best comparables on here were Ehlers and Forsberg (Forsberg also had back-to-back 60+ point seasons, though he did it with worse linemates and scored more goals). 6.5M would have been 8.17%, which would have been more than fair.
As for Matthews
Stamkos 5 years X 11.66% (Stamkos had a Rocket Richard + finished 5th in NHL scoring in his 2nd season)
Kane 5 years X 11.09% (had finished top 10 in scoring and won a Cup)
Toews 5 years X 11.09% (had won a Conn Smyth, a Cup, and had pretty similar point totals to Matthews after 3 years)
..
..
..
Matthews 5 years X 14.63% (despite a career high of 73 points, and never even projecting to be top 10 in points even if you ignore injuries). He was given McDavid/Malkin/Ovechkin money, despite them winning Art Ross trophies during their ELCs and Matthews never even projecting to finish top 10.