Bad teams with new coaches that want to make a splash with big passing games kill young QBs.
Solid teams that can lean on the run and play-action give a chance for QBs fresh out of college to grow and learn how to dictate a game.
A lot of these guys, and maybe even Bryce, aren't horrible but they are being asked to go in and be something unrealistic. They are expected to be able to put out raging dumpster fires after being handed a bucket and being told to go find some water.
And I think we see some of these guys who were labeled as busts eventually developing into serviceable, sometimes decent, sometimes quite good QBs when they land at a well-built team with good coaching and a solid identity. Mayfield, and Darnold are two that come to mind right now. And the two Joneses are certainly showing more in Indy and San Fran than they'd ever really shown before.
But we're a shoddily built team that has been weakly coached into a softer style of football that puts crazy amounts of pressure on young QBs. Heck, even Andy Dalton with his experience really couldn't sustain any results here.