FIBA Basketball
One single board in the floor was warped a tiny bit
Look at the end when he drops the ball in two different spots see how it doesn't bounce as high both times
Essentially it’s the deviation from muscle memory of a task that alerted both this basketball player and the engineer that found the xz back door.
In this case, the player had dribbling the ball down to perfect muscle memory and when the ball suddenly flew off in the wrong direction, he realised something was wrong, and investigated the floor.
Similarly, the engineer ssh’d into a particular server on such a regular basis that the one time that it took 500 milliseconds longer than usual to complete, he took notice and investigated the system.
In both cases an extremely minor deviation from expectations was key to uncovering the flaws.
