Obviously the two wheels in the back didn't have a lot of traction. I've never slid a mower when the rear wheels have traction. It's only when they break loose is there a problem. If I ever find myself nose-down a steep hill, which I try to avoid, but sometimes it's inevitable, I pretend I'm driving my truck on ice. Pull back the sticks in fast jerky motions, like pumping the brakes on a car. When somebody pulls the sticks back going down a hill, it's a guaranteed slide. The rear wheels are going too fast backward to stop the machine. In order to stop the machine, the tires need to be going the same speed as the machine. The tires are what make contact to the ground. If you can slow the tires, you can slow the machine. In a slide, front brakes and controlled reversing sticks will stop almost all slides.