Would you pay Brock Purdy $55 million a year to be Saints franchise QB? [mod edit]
Geldo's right on. Strictly, prime Peyton Manning and Tim Brady were system quarterbacks to the extent that when they moved on to different teams, their offenses went with them. Manning in Denver and Brady in Tampa, respectively, were their teams' de facto offensive coordinators (for Brady, after a few games wrangling with Bruce Arians).
If you put either of those guys, in their primes, on the Dennis Allen-Pete Carmichael 2022-23 Saints and forced them to run exactly the plays Carmichael called (no "Omaha" stuff at the line), they'd have looked only a little better than Derek Carr looked. Let them run Manning's "Tom Moore" offense and the stuff Brady & Josh McDaniels cooked up in New England, however, and even Dennis Allen's Saints would've been a contender for the NFC title.