3. The differences in mechanics
Digging further into this, the irony is thick that the Caleb Williams-over-Justin Fields' camp, is very committed to overlooking Williams' very poor second-half play in 2023 but emphasizing his moments of 2022 brilliance. On the other hand, the Williams' camp insists on focusing on the many mistakes Fields made in 2021, 2022, and the early part of the 2023 season. It is poor judgment in the extreme to ignore the substantial progress Fields made in the latter part of 2023 while also ignoring the regression of Caleb Williams in 2023.
To quote Chris Simms when Justin Fields was a prospect, "His footwork is all over the place." Knowing how hard it is for QBs to correct their footwork flaws once they come to the NFL is why I was against the Bears drafting Fields. Yet, here we are three years later and Fields accomplished a rare and difficult task. He made genuine progress in fixing his footwork as well as his upper body mechanics. Fields' footwork still needs more fixing but it, certainly, appears a case can be made his footwork overall is much better than Caleb's footwork. The reasoning here is that operating outside of the pocket Justin Fields is an accurate long ball thrower. If you add this to his improved footwork in the pocket, his overall footwork is better than Caleb Williams' footwork. So this means replacing Justin with Caleb would be a step backward for the Bears in the very important matter of quarterback mechanics.
On top of this, Williams played in a simplified offense that used one-read concepts. Whereas in the second half of 2023, Fields made considerable growth in going through his progressions, making good decisions then delivering accurate throws.
To be fair and inclusive in our QB comparison, here is another angle on Fields' less-than-perfect mechanics. In the pocket, Fields has this annoying habit of taking a short bounce before he makes a throw or taking a step backward before he takes a step forward when making a pass.
Another aspect of Fields' accuracy is when he is making short throws. In these plays, he appears to lose full focus on placing the football to maximize yards after catch.