Saints planned to interview Mike McCarthy; McCarthy didn’t garner enough interest from Saints and will take a year off

Exactly. The problem just shifts from “future management issues” to now having to limit yourself in order to maintain the healthy cap illusion.

There’s no perfect style when you consistently bet on the wrong guys.
I also think it's more of a problem of not getting the right players or not developing them, than it's a problem of salary cap management.

If Carr is the starter this year and plays at all pro level, then there aren't any issues with his contract at all. The reason people see it as a bad contract is because they feel stuck with a bad QB. If the Saints had any of the QB's that played this past weekend under that contract, very few people would think the Saints were stuck with a bad contract.