The stability ball ab rollout is a great exercise if you don't have an ab wheel available. But it's also a good choice if the standard ab rollout is too difficult for you right now.
It's essentially a partial rollout since your body isn't going down as far. You can start with a large ball, move to a smaller one as your core gets stronger, and finally do the ab wheel with the full range of motion.
Dan John is Testosterone's Yoda, wise as hell but with better skin and a heckuva' lot higher PR in the snatch than the original. However, our Yoda has had his share of Yodas to learn from. Read here as he shares his most valuable weight-lifting lessons.