Middle and senior management, not grunts. The "grunts" ratted out the bosses. Even Wikipedia has that much info.
None of this is new really. The ATF has had a built-in cultural dysfunction in middle management ranks for decades. Intense arrogance and zero accountability lead to bad decisions.
Such attitudes created the Ruby Ridge and Waco incidents. Countless lesser disasters that rarely make the news too.
Every time, the ATF can count on the American left/right political battles to take focus off the agency. People may get shifted around, but no real punishment is given.
We shall have to wait and see if anything meaningful comes out of this.