Pretty crazy Burrow stat

[Essex Johnson]

Impressive stat, especially some of the differences vs Burrow's smaller difference but not much real data behind the post. How does he define unpressured? more context would be better, i think a great stat would be ball release connected to it. What is the average ball release of these QBs unpressured vs pressured and what percentage of throws of QBs are pressured and unpressured. That would give more substance to this chart