Hi Luis,
Yes, Anson raised these same concerns in his presentation. He said that after checking is old very research intensive process as compared to the formula shared above, that he did not find a deviation between the hedge funds identified in the traditional process and the above formula.
I myself used to intern at a pension consultancy and we developed a formula for quickly identifying great managers (that included semi-standard deviation, by the way) and we only occasionally disagreed with the findings of the formula.
With smiles,
Jason