First off, you can't give a veteran a $0 base salary. You at least have to pay him over $1m.
Secondly, why would Cousins do that? The tag number is $24m for the first year. So, if you are him, you are starting discussions at making $30m guaranteed in the first year (if his agent has half a brain).
The Broncos has some other spots to fill on the line and they have some guys to resign on the defense with $36-40m in cap space. It is not necessarily a cap space issue, but if you pay big for a QB, then it will impact you in other areas and Cousins is not a guy that you want to mortgage your future for.
I'm not a cap expert, so if it's a minimum $1 million base, then make that his base then I guess. Wouldn't change that much from my base idea.
And the "why" for Cousins to do that is he wants the long term deal from everything I'm hearing, so perhaps they guarantee him $45 million-$50 million, which gives him insurance against taking the $24 million franchise number again and potentially getting hurt. Most players don't seem to want to play under the franchise 1 year tender (let alone for 2 years) even if it's more money in that first year and would trade that for more long term security; and this would be presuming of course that Cousins just doesn't want to re-sign in Wash long term anyway.
And the "why" for Den would be they can't seem to win with what they've got. You're right that they have other needs on both the o-line and defense, but they can't win with what they have at the QB position, so all the other moves are for naught if they still go into the year with Lynch and Siemian as the guys. Considering Elway before was able to bring in Talib, Ward, Ware, E Sanders, and re-sign Chris Harris all while still having Peyton's huge contract on the books, then if anyone was going to find a way to work around the cap for a deal like Cousins (whether he deserves it or not) you'd think Elway would be able to.
To be honest, this was really just a spit ball idea back when this discussion was going on, so I didn't put a ton of thought into it. Just saying "could" be a possibility if Cousins was really adamant about leaving, that's all.
4-2; 2nd place overall, first in total points
R WILSON, mariota
M GORDON, MONTGOMERY, McKINNON, d. henry, b powell, r kelley
AJ GREEN, HILTON, D PARKER, e sanders, c davis,
GRONKOWSKI, greg olsen (IR)