there is no set number to know whether the qb has it or not although referencing guys who started their careers over 20yrs ago to fit your narrative is not gonna work, brees and warner are not even remotely close skillset wise to fields and while young has similarities, he played when it was a much different game...
if you want to reference guys as far as 10 yrs back it would make much more sense, teams cant keep waiting especially when qb contracts are getting larger and larger...Guys that have similar skillset to fields, wilson, rg3, newton, jackson, allen, mahomes, trubisky*, watson, love*, prescott are the only ones i can think of. Everyone listed without an asterisk balled out within 2 seasons...
Trubisky while he did statistically ball out in 2018, anyone who watched that season knows it was the defense that helped carry them.
As for Jordan Love, is jury still out on him?
According to you, love still needs developing because he has only played in 16 games...i'd be willing to bet that the packers know right now that love is not the guy no matter how much development happens between now and the end of the season and they will be looking to draft his replacement this year.
brees did not get traded, he signed with the saints as a free agent, it was between the saints and dolphins but concerns over his shoulder he choose the saints because they gave him a better deal