If names you've never heard of start popping up in your blue-chip fund, consider this a yellow flag. Another flag should go up when you see an equity manager starting to stockpile cash. That means the fund is either growing too quickly and has no place to invest new money or the manager has changed tack. That's what happened to Foster Friess and his Brandywine Fund in 1997. After a trip to Asia, he concluded that the Asian Contagion would rock the U.S. markets, so he loaded up on cash.
Market timing is controversial, but there is nothing wrong with it per se.
Just make sure the portfolio managers you bought into for other reasons don't change the game on you in midstream. Everybody loves a winner. That's why hot funds attract so much money. But too much business success can be destructive. Managers can't invest fast enough.