RE: Diving on downwind?
Yes, planes don't fly different in steady wind. The only time wind will affect handling is if the wind is changing velocity (either speed or direction.) Because of plane inertia, drag, etc., the plane will react to gusts. But a steady wind, no, the plane flies just like it does when it is dead calm. The only time steady wind becomes a factor is when the plane interfaces the ground, i.e. takeoff and landing, but even then the only diff is ground speed vs. airspeed... this is why planes takeoff/land into the wind, to gain the most benefit from the wind and to reduce ground speed required.
I'll throw out a bit different observation. It might be an illusion. From our reference as a RC pilot standing on the ground, downwind flight looks very fast. I often see many throttle back on downwind, or make an aggressive turn to downwind which kills airspeed, all due to the illusion that the plane is not performing as expected, so the pilot compensates. The illusion occurs because of our perspective of being firmly planted on the ground. Double whammy is the aggressive turn with throttle back. Pilot is "tricked" into thinking they have plenty of airspeed, or even excessive airspeed because downwind passes look fast. I'm not saying this is the issue, but I've seen it effect pilots before.