Far far less than half of companies succeed. So identifying successful companies by random draw is not equivalent to a coin toss. In the case of this study, its 10%.

55% on A-rated companies is way better than the "coin-toss" model of randomly assigning a rating to each company, because there are more than two ratings.

I apologise for ever posting this trainwreck of statistical reasoning. I don't know what I was thinking.