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Fleet yaw is a different phenomenon that impacts terminal ballistic performance. It’s essentially a way of describing why some projectiles tumble and fragment after impact while others will tend to remain more stable and pass straight through for longer.
The projectile AoA being described in that context is only a couple of degrees. It’s enough to change how the round behaves after hitting something, but it’s not the type of in-flight wild tumbling that results in keyholing on a target.
This is an important clarification, you’re right. The yaw angle is minimal in ballistic flight, the level of keyholeing in the photo is rather dramatic. Though the 5.8x42mm is standard with a mild steel penetrator like M855, and the round was definitely built with cost as a major factor - maybe a bad lot of ammo?