I don't know about HR/9, but everything else in this post is correct. With regards to H/9, it's implemented in the opposite way of the Solid Hits slider, or the Contact attribute on a batter. A higher H/9 rating means the batter is less likely to hit the ball solidly. They have less leeway on where the PCI can be while still hitting a line drive or hard fly ball. A low H/9 rating means your PCI can be slightly off the ball and you still have a good chance of hitting it well.