This may be a little off-topic, but, since there are more experienced people here, I think it's right to ask.
Do you think that one can defend (him/her)self from a grappler with Aikido techniques, on the ground? I don't mean the "a successful Aikidoka wouldn't go to the ground in the first place". Let's pretend that you fell to the ground.
Picture of O'sensei on the ground (newaza). It looks like he is defending himself to me. I think if an Aikidoka found himself on the ground he/she would do something similar to this picture.