I believe the markets are assymptotically efficient, but because of constant changes/surprises and the mechanisms being chaotic, it never reaches steady state, and thus is never actually efficient. There might be individual stocks or sectors that do reach steady state between annual reports, but as a whole: no. It's possible there's statistical signal in the inefficiency, comparing predictions to outcomes. At least HFT seems consistently profitable, and whatever Medallion is doing.

That said, judging if one specific trader is lucky or good is practically impossible.