I agree that efficiency depends on time frame, but I believe that the market will always be more efficient as the time-frame grows. A market is not zero sum. Investors with long-term horizons don't have to beat the market to make money, because wealth is created.

"Since short-term traders contribute more heavily to efficient markets than long-term value investors, it's plausible that long-run investors can make expectancy in excess of the market average."

Why do you think short-term investors create more efficiency than long-term investors?