@203Pat I guess the best term I can come up with guys for like Mac Jones, Gee No Smith, Brock Purdy, etc are "replacement level starters". You play them if you have to, but if you can find a better replacement you play that other guy instead.
I think it's pretty distinct from guys you simply can't see as ever being a starter. For me our own Josh Dobbs falls into that bucket. I don't know why he still has a job here or elsewhere, other than perhaps he's a good character guy. If he has to play significant games, IMO our season is over. I don't see him taking a team 4-1 like Mac Jones is doing in SF. I hope it never comes to that, and if it does, I hope I'm wrong.
Some of these QBs like Purdy, Trevor Lawrence and Tua Turndaballova are on big contracts, but that shouldn't really be a factor, they should be replaced if their teams find a better player. They get the big contracts because their team hasn't found the better player, yet, and they had no one else when their contracts were up. Late period Russell Wilson falls into the replacement level bucket too. Huge contract in Denver but needed to be replaced, then the same thing happened in Pittsburgh and now New York as well.
All of these are distinct from "franchise level starters". That's when you are confident that you have a guy that can take you deep into the playoffs if not all the way. Some people seem to equate "starter" with "franchise level starter" but I see two different categories, "replacement level starter" vs "franchise level starter". Their "backup" is my "replacement level starter" because we do see a lot of these guys starting game after game after game so calling them a backup doesn't work for me.
And yes, my thinking is heavily influenced by watching a lot of podcasts such as ATN, HTC, Mina Kimes, etc.