Here, a perfect example of it.
https://streamable.com/zx7k7
I didn’t know that McCree was behind, I was simply trying to get the healthpack. However, I heard the footsteps and combat roll and I preemptively blinked to avoid anything coming my way. And I did.
And in so many games I saw people brutally ignoring sound cues and getting flanked and caught unprepared.
So, turn off your music, turn on your sound effects, get a good pair of headphones and try to listen for it.