Let me preface with the caveat that I have not been in any 'real' fights.
Primarily, I want to agree with James Bostwick how said that one aspect of being a 'fighter' (as opposed to a martial artist) is that you lose some of the time and that a lot comes down to luck and natural born instincts and reaction times. I also agree with Mike Lee that training can make a real difference. I guess what I was thinking about was a quote I read once from one of the O Sensei's american students (anybody know which one?): "AiKiDo should be judged not with respect to the objective level you reach, but with respect to where you would have been if you hadn't studied AiKiDo. Without AiKiDo, my natural aggression would probably have turned me into a serial killer. So, even if I don't embody the spirit of 'loving protection for all things,' I still feel that it has saved me."
I have no doubt that I am a better fighter now than I would have been without AiKiDo. I hope to never be forced to find out how good that actually is.