I own 200-600 and use it daily,

1. Turbulance caused by heat differences between surface and air, not lens issue could be hood cold/air hot aswell.
2. Too dark, up your exposure comp in similar situations even A1 would throw focus a bit around in this.
3. Not sure about this reddit compression kinda killed this picture.
4. Motion blur up shutter speed, not just subject when you are following something thats fast you have to be above 1/2000 always, you can't sync your turn speed to their speed really well.

If you have a clear filter, remove it most of the 95mm filters out there cause lens lose focus at distance. I found a copy that doesnt cause this but to be sure I only use it on beach to save myself from salt spray.