"Most people aren't cut out for value investing, because human nature shrinks from pain," the money manager Jean-Marie Eveillard told me this past week. His words are a reminder that making money on cheap stocks—the goal of every value investor—is harder than it sounds and can take years to play out.

Lately, value investing has seemed easy. Over the past year, the Russell 1000 Value Index, a yardstick of cheap stocks with sluggish expected earnings, is up 19%, compared with 11% for pricier "growth" stocks...