Is his ability to read defenses. He's got all kinds of upside sure. Fans and media are all over that. But in getting the ball out decisively to the right target he's a projection and one that might need a whole lot of time to develop. And in that window of development you're running read-option and half-field reads and designed runs to use what he can do.
Enter the 9ers who know they need to compete better at QB to stay with the 2021 Rams. Will they really give up 3 first round picks for a guy they have to wait on? The Rams defense will EAT Fields year one. They'll probably eat him year two.
People want to knock Jones but the guy gets the ball out quickly and decisively and finds the right targets. Good accuracy too. He's no top pick in terms of talent but he's a play-quickly QB and that my football friends has a lot of value. The 9ers might actually get most of that 5 year window from him on the actual field playing the game.