With respect, for the player, a contract extension is about compensation. I think that we should spend at least some focus on what compensation you expect Brady to agree to for 2020 and 2021.
EXAMPLE
Brady agrees to $23M salary in 2020 and $27M in 2021, with everything guaranteed.
Brady agrees to a 2019 salary of $3M.
$12M of this year's cap is a result of old contracts and cannot change.
ANALYSIS
1) Brady to agree to a $12M bonus, moving 8M to future years. This gives Brady ZERO extra money this year, and a non-competitive $25M a year for 2020 and 2021. Brady might take this.
2) 2019 CAP = $12M old plus $4M new bonus plus $3M salary = $20M 2019 cap
This is a 2019 cap reduction of $7M.
3) The 2020 cap hit would be $23M salary + $4M bonus = $27M cap
4) The 2021 cap hit would be $27M salary + $4M bonus = $31M cap
BOTTOM LINE
A) Do we expect Brady to be paid less than $25M a year? I don't.
B) Do we really want the cap to $16M, $27M and $31M. I don't.
C) I think that a $9M salary is much more reasonable, moving $6M forward for a cap savings of $4M. Cap hits would be $21M, $25M, and $29M. If Brady agrees to different that $23M and $27M in 2020 and 2021 salaries, I wouldn't change the bonus or 2019 salary.