He's not a particularly good QB, he's just in a really good situation. The last couple years have been great examples that QBs can be in the wrong situation, good somewhere else and do well. Sam Darnold is suddenly balling in Minnesota. Malik Willis went to GB and playing well. Were they bums in the past, are they good in the present, or are they simply in much better situations now. I think it's a bit of each but the biggest factor is better situations. Fields has a good o-line now. He didn't have that in Chicago. He also has a good defense. Chicago's defense was pretty meh until his final season there. So he has a clear pocket, multiple weapons, and his defense isn't putting him in terrible situations.