They say size doesn't matter ... as much in jiu-jitsu. I will say I've had my rear end handed to me quite a few times by people who were smaller than me but higher-ranked and more skilled. However, I will say size/strength does narrow the skill gap pretty considerably, I'm finding.

Last night I was rolling with a guy, and he was considerably smaller. We started in close guard, and I just stood up and picked him up. He immediately stopped and told me, "I'm not about getting slammed to the ground." To be fair, I'm not going to do that in the gym, but it was a quick reminder that sheer size and strength do have their advantages. When your opponent can simply pick you up off the ground, technique can only overcome so much.