By physical strength do they mean stamina or something along those lines?
I think it means muscle strength. And power is how hard they can hit the ball. It would be affected by technique, height, weight, and aggressiveness, so it can be distinct from strength. Yukikaze is overpowered for her size. As expected of a destroyer, she lacks reach and stability. She bounces off the ball.
Usually 体力 in stats like these means stamina. For these charts physical strength would be more or less reflected in power. So Yukikaze's low power would reflect that she's a destroyer, but she has off-the-charts stamina probably based on her historical survivability.
