My very broad brush strokes take would be that good QBs are positive force multipliers.
If the support structure around them isn't viable, they can't necessarily negate that problem, but they increase the value and effect of other good things in the offense.
So you're paying them for the catalyst effect they can have. You shouldn't pay them expecting them to turn chicken shit into chicken salad.
Given the Herbert & Jordan Love discourse this week, I feel like folks can only come to one logical conclusion: These quarterbacks must be massively overpaid!
They’re compensated as if they can uplift their situation, but turns out they’re totally helpless!