Cool test, results you can see and some literature to back it up. If you are interested at all in proprioception, this is an interesting read.
So, the question for us is: "Does ankle dorsiflexion actually create more stability, like is purported?"
“The point is that if I make their ankle rigid this way, then they can more effectively use the balance mechanisms at their knees, hips, and proximally, because they’re on a stable base. My proposition is that their balance is actually normal, apart from that distal segment. When their ankle is stabilized, they use their knees more effectively, and they become less dependent on their eyesight to maintain their balance.”