That means a flood of money is flowing into these baskets of stocks daily, and it doesn't discriminate between the fundamentally sound stocks and those that have problems. But the fact that many investors have given up on trying to pick quality stocks has actually created an opportunity for those savvy enough to try.
I took this to mean that since the 'herd' is plowing into ETF's, the opportunity to outperform is via well selected individual stocks that are currently out of favor relative to the overall market as defined by those index transactions.