A quote from your second source: The average subsequent performance of the historically best- and worst-performing long U.S. equity hedge fund portfolios is practically identical and similar to the market return.

A quote from your third source: Due to hedge fund mean reversion, yesterday’s nominal winners tend to become tomorrow’s nominal losers.

So, it seems like there are differing conclusions based on how you slice the data. I'm familiar with mean reversion, but I don't understand why this would predict underperformance for outperforming funds. If you flip a coin 10 times in a row and get heads 10 times in a row, you don't expect to get heads less than 50% going forward (but do expect the average rate of heads to trend back towards 50% over time).

Furthermore, if OP's strong claim ever held true, surely there would be funds that outperform by simply indexing the broad market minus the holdings of top performing hedge funds. As more and more money gets invested in these new inverse fund, the pattern the strong claim is based on would slowly cease to exist. Unless you're saying the underperformance is due to fraud or exorbitant fees.