The Sharpe in the ranking log is using an annualized performance. So if EBAY had a 9.481% performance for the 16 trading days, this would sum up to 316% for the 252 annual trading days (=1.09481^(252/16)-1). The 18.846 Sharpe is 316 divided by volatility. As we use this only for a ranking we would in fact not have to annualize. The ranking would be the same but annualized you can compare it better to other Sharpe values. It is clear that we get extremely high Sharpe values if a stock performs nearly 10% in 16 days.
Finally, we do not rank directly by this Sharpe, but by the attenuated Sharpe which can give a higher weight to the volatility. This Attn Sharpe is only used internally to rank the stocks.