Last year Saints had the best QB in the division and couldn’t win it. It’s officially no longer the case and Baker may have even passed up Carr by the end of last year.
Anyone that thought Carr was the solution at QB to turn the Saints into a very good team was kidding themselves. But, the same is true of Cousins with the Falcons and Mayfield with Tampa. All of them depend on the team and talent surrounding them. They are all very close in terms of level of QB and who looks better will depend on who is in a scheme that fits his talents and the talent around them. The issue for the Saints last year is they had a terrible OL that couldn't pass protect for half the year, couldn't run block for the entire year (maybe due to scheme), and did have a contested catch/red zone receiver. If that changes this year then Carr will look as good as Cousins and Mayfield meaning they will all be in the range of #10 to #15 QB in the NFL depending on the year. The major difference is Mayfield still has time to learn, Carr still has a little upside in the right system, and Cousins is at best likely to stay the same or regress slowly from age 36 on.