How? Lesser career Rating, way worse completion percentage, close on TD to INT ration. Mac Jones is a better passer, Fields is a real good runner, so I guess slight advantage to Fields. Of course, running QB's wear down and get hurt.
Even in this current year, where Jones clearly has been shell-shocked, he's only slightly worse than Fields, who has the best WR of the 2 teams in DJ Moore.
I've watched the last 2 Bears games with Fields, I think Jones has more potential as a passer, but both will never be good starting NFL QB's.
Fields is around NEGATIVE 20% below expected EPA in the last 2 minutes of a half and the game. That's when QB's show what they have. That stat is at the level of guys that can't even make careers as backups in the NFL.
Fields shows some wow play with his feet, so teams think he has potential, so teams think he is worth more than Jones, but since they are backups only it really depends on the team and system. In SF Jones would fit better, at Ravens then Fields would fit better, as backups.