"As to a cap friendly deal, you put a large percentage into a signing bonus and this keep the overall number on the contract down."
This is false.
Okay. Now I understand your position. You don't understand cap management. Perhaps I can provide an example to illustrate.
Let's say our team wants to sign (or extend) our QB. We know the going market for a QB with our guy's skill set is about $20M per yer and we want to sign him for 5 years. So now we need to figure out how to allocate the funds.
We could put 20% of the total $100M contract (5 years at $20M per year) into a signing bonus and then front load the contract a little. Something like this:
Signing Bonus: $20M
Yr 1: $18M; Yr 2: $18M; Yr 3: $16M; Yr 4: $14M; Yr 5: $14
Or we can sweeten the deal up front and give the player a little less of an overall contract:
Signing Bonus: $40M
Yr 1: $6M; Yr 2: $10M; Yr 3 $10M; Yr 4: $12M; Yr 5: $16M
So we are paying the same QB $6M less overall over the same term.
Why is this second contract good for the player? Because the guaranteed money is much more up front. He's getting $20M more before he ever plays a down, and his overall compensation after 2 years is exactly the same. That's a great lollipop given that players (and agents) know that a career can end at any time.
Why is it good for the team? Well, beside paying the same player $6M less over the life of the contract, the cap hit early on is less: $9M less in Yr 1 (the annual plus the bonus split over 5 years) and $5M less in Yr 2. When the cap hit starts getting greater it is very likely that the overall cap number will rise enough that the impact will be much less. It also has some positive attributes if the team cuts the player late in the contract since it is back loaded.
The drawback for the team? They are taking greater risk up front with that huge signing bonus. It will cost them a lot more to cut the player if he craps out early or gets a career ending injury. But that also is why the team can sell the smaller contract to the player.
This is a pretty simplistic example, but it happens all the time for cap savvy teams. They understand how much risk they are willing to tolerate and they are rewarded long term in their cap management.
Hopefully this will help you understand how contracts can be adjusted to help both the team and the player in certain situations.