Much was made of the Sox' "neuroscouting" in discussions of Betts, whom they identified pre-draft with a video game as someone who might have elite pitch recognition. But I suspect that there is a similar story about Bradley.
Bradley is the distinctive player of the Statcast era, which corresponds roughly with his career. What it has revealed is that on many of his best plays, he "reacts" before the batter makes contact, moving in the right direction only two tenths of a second after the pitch has left the pitcher's hand. This is absolutely amazing to me, and it has revealed the particular source of Bradley's excellence.
But the Statcast Jump stat has three components, "reaction," "burst," and "route." Bradley is so-so at burst, and actually has poor route efficiency according to Statcast. But he is the runaway leader in the "reaction" component.
In 2016, he was 1st.
In 2017, he was 1st again, this time by an outlandish margin, separated by the 2nd ranked CF by as much distance as the 2nd from the 12th.
In 2018, he was 1st.
In 2019, he was 1st.
In 2020's small sample, Bradley was 2nd by a small margin behind Trent Grisham.
I submit that that is a rare level of dominance in a single stat, especially during a golden age of CF defense.