I think it was Tim Jenkins who said something that i wish more of these QB gurus would mention and that's that most people who evaluate Fields film don't understand what its like to be one of the best athletes on the planet. When you can blow by an entire defense like Justin can, it changes the processing math. I dont think this is something Warner understands as he watches everything through HOF pocket passer eyes. Out of everyone who has broken down Fields tape, he seems to be the least nuanced.
The reality is teams throw because throwing generally results in bigger plays at the expense of more risk (sack, fumble, int, incompletion). There is usually a 3 or more yard difference between YPA and YPC. However for the Bears Fields YPA is 7.2 (14th) and his YPC is 6.8 (2nd). So that is only a half yard difference. In that scenario the risk reward structure is out of whack. The additional risks of throwing are not actually resulting in higher rewards ie just a 0.4 yard difference and thus from a purely risk reward standpoint, if there is any concerns about risk, you should run not throw.
Consciously or subconsciously I suspect this is the internal struggle Fields is battling. Does he hang in there and try and throw the ball risking 4 bad outcomes or does he just run knowing his bad outcomes are less and because he is so great running, the reward for running isn't all that different than it is for his passing. This is likely why Getsy is calling so many runs and is probably fine with the scrambles. There isn't a low lot of difference for the O if Fields runs for 6.8 yards vs throws for 7.2 yards but again the former is safer than the latter.