As a grappler myself, I think that your best bet is to keep moving, and most importantly, DON'T LET HIM GRAB ANYTHING.
If he's any good, he knows that there's a couple of things he can do with everything he grab.
Also, beware of the takedown. Us BJJ guys also have unorthodox takedowns which have nothing to do with wrestling.
When we go to the ground, you are in my world. The ground is the ocean, I am the shark, and most people don't even know how to swim. - Rigan Machado