This is actually the best year to evaluate who deserves the lions share of credit for the Patriot dynasty. If Brady can elevate a perennially mediocre team to a super bowl contender while Belechek is struggling, i'd say that speaks volumes about Brady.
Its not the same thing Atlanta...
Brady was able to get together with players in the off season... much was made about him getting together for throwing sessions, meeting the the tampa OC... And Brady going to a perennial mediocre team, who was chock full of offensive weapons
and in New England, all otas were cancelled etc, camp was restricted, teams and players locked out of facilities, players opting out of contracts because of covid, ad nauseum...
and this is the level playing field you want to use to determine who is more responsible for the dynasty?
The argument has just begun... the answer is not going to be determined in 8 games, or 16 games... Gotta let it all play out... then you will have your answer
(answer to the question: its both of them)