The cap was out of control at the time because of extending (and tagging) players from the same draft class all at once. Along with existing cap hits to prime Cam Jordan, prime Michael Thomas and Drew Brees’ dead money. That many star draft picks due for a new deal at the same time isn’t talked about enough as the reason why the kicking the can started.
Someone was going to be the odd man out in extensions between Lattimore, Ramczyk, Williams, Kamara, and Hendrickson. They were all 15M+ players a piece in new market value AAVs after their rookie salaries. Combine 4 of those 5 with Thomas and Cam, and there’s 90-100M salaries tied to 6 star players. IIRC all of their contracts were front loaded in huge bonuses which made the cap hits bigger in the 20M-30M range at the beginning of the deals.