[jofer]

I believe he was referring to the "put my brain in G" comment.

It's all about recognizing when to build tension and when to resolve tension.

Yes, the roles that the notes play is defined by the key, but if you don't mentally make the switch, you'll often perform things poorly because you don't anticipate where things are going correctly.

Or at least that's how it works for me, at any rate. Take anything I say with a grain of salt. I can't sight-read much at all.