I would love to have Darnold here and Brissett GONE...I would be doing mental cartwheels.
Darnold would also have a chance to develop and mature here without crazy pressure.

Didn't realize this until I saw him playing today, but Flacco has started the last 2 games for the Jets. Is Darnold hurt, or did he get benched?

He was injured in the Jets loss to Denver. He hurt his shoulder on a play in which he was sacked and thrown to the ground by a defensive player.

First sign of a Jets purge?

https://www.profootballrumors.com/20...-to-buccaneers

They also took a big step forward toward the first pick in the 2021 draft, because two of their competitors (Giants/Falcons) both won their first games today, putting the Jets firmly in the driver's seat as the only remaining zero-win team.

It should be an interesting few weeks for them. If they are planning to tank, it would be best for them to get rid of Darnold before the trading deadline.
The question is whether the Colts would be interested and, for that matter, whether the Jets would be interested in trading him to the Colts - as that would be particularly embarrassing for the Jets given that the Colts essentially traded Darnold to them.

Darnold is 3 years into the NFL. If he's not developed by now, then he's not going to. He sucks. You can blame the jets if you want, but good players will become good players despite a bad organization. He isn't any better now than when he was a rookie.

Drew Brees, Warren Moon, Brett Favre, and Ryan Tannehill all disagree with you.

Brees in his 3rd year starting went 11-4, threw 27 td's and 7 int's
Tannehill in his 3rd year starting threw for 4000 yards, 27 tds and 12 ints
Favre in his 3rd year starting threw for almost 4000 yards, 33tds and 14 ints

Brees and Favre both took their teams to the playoffs those years.

The 3 QBs you're talking about were 25, 26 and 25 in the year you mentioned. Darnold is only 23 right now. No guarantee he will be anywhere near them, but he's got 2 more years before he even gets to their age. Still has a chance to develop into a star. I think in his young career he's had several coaches and OCs and a very porous OL. I wouldn't consider him a bust yet, and if you could get him on the cheap, it's worth the risk. Unless they re-sign either Rivers or JB, they save 46 million in cap hit after the season.

They were that age mainly because they sat behind established starters, but the experience is what matters. If you are in the 3rd year and you are as bad in your 3rd year as you are as a rookie, then the chances of that person panning out as a franchise QB are slim.

If they want to get him as a backup, that's fine. Maybe he defies those slim odds, but I wouldn't put the franchise in his hands and expect it. If we do that, we may just waste more years in QB hell.

You are fudging here. The Brees and Favre years you reference were actually their 4th years in the league. You skip over their first years just because they didn't play much. If you skip games they didn't play, then Darnold is still in his second year - he's missed 8 games so far. So to be fair, here's a comparison of their second years:

Brees - threw for 2108 yards, 11 TDs against 15 INTs
Tannehill - threw for 3912 yards, 24 TDs against 17 INTs
Favre - threw for 3303 yards, 19 TDs against 24 INTs
Moon - threw for 2709 yards,, 15 TDs against 19 INTs

Incidentally, you omitted Warren Moon from your analysis. In his third year, he threw for 3489 yards, with 13 TDs and a league-leading 26 INTs. He was also 30 by then, so he was probably not someone who appeared to have a bright future at the time.

Ultimately, though, the point is that these players all underperformed at first, but later hit their stride - most of them with heir second team I'd also venture a guess based upon the W-L records of their teams during their first few years, that none of these guys had supporting players as dismally bad as Darnold does (Brees 2nd full year his team went 2-9 while he was QB, so maybe that year is close).