Bagent got the ball out quick, and also the Bears run-game was legit effective. Those two things help prop up a bad OL that struggles to pass-protect their QB. Fields has struggled in this area. Bagent didn't.
Getting the ball out in 2.5 seconds accurately and with GOOD decisions is the most universal trait of the top NFL QBs. I believe it is mostly innate. The guy either has a brain that can do this or he does not. It appears that Bagent has it, and Fields does not. Neither does Lance, Jones, Wilson. Trevor Lawrence has it. He is 2.39 seconds.
I think that's true too. Yes, the game can "slow down" a bit as a young college kid transitions to the NFL as QB1. But having a truly elite QB1 mental processing power is something you either have or you don't. If you don't have that attribute it's like an old computer with an ancient CPU. That old CPU can't match a fast-processing computer. It just can't. Same with a QB1 who lacks that mental CPU processing power.