I did not say Simms was interesting. I said it was interesting that he said that there are not many people in football that really understand quarterback mechanics. I didn't even say I believed him. Was a provocative statement. Maybe he's full of shit. Maybe there is some truth to it. Idk.
There may be a hint to it. Alex Smith talked about it during a recent interview with Cowherd. He commented that Reid was basically the first coach he had that talked mechanics with him. The example he used was: You throw a ball too high in practice. Some coaches will just say, "You threw that too high, throw it lower" in a big no shit sherlock moment. But, he said Reid would be like, "You threw that too high, let's talk about what you were doing on that throw and if we can change it".
So, there is probably a degree of NFL coaching that gets too caught up in the schematic side and less on the fundamental side. However, my impression for the Bears is that they have one of those fundamental guys in coach DeFilippo. I am honestly not sure where Nagy and Lazor are on that scale. There is a lot of talk about Nagy and his scheme, but there hasn't been much talk on fundamentals. Reid spoke highly of him once upon a time, so there is a chance it exists and it just doesn't get talked about due to issues with Trubisky.
And with Trubisky, it's so hard to say what all went wrong with him - it was likely both fundamentals and scheme. There have been hints in various reports though that they tried to change/improve his fundamentals. And to a certain degree, it might have messed him up more - made him think too much on top of him already thinking too much due to the scheme.
Either way, Fields is the make or break for Nagy - both for his ability to show that he (and his coaches) can develop a qb and that he can scheme an executable NFL offense. Not just a nifty play here and there, but be able to put together a cohesive offense that guys can execute.