However, I notice that when I'm panning in tight corners, I almost always wind up with a very small target area in focus. I try to track the driver when I can, so in this example, the helmet area is sharp, but the front and the rear of the car aren't. At F/5 and a distance estimated at 7m or so, I know I don't have a huge DoF, but I'd expect at least 1.5m of the car in focus, and it's not even close.
The biggest difference between these two (and other examples like them) is that the car is moving straight across my FoV in the first shot, but it's moving in an angle in the second.
I've seen this in dozens of panning shots in tight corners (and really only in panning shots), but I'm at a loss to explain why it's happening.