Duan,
You aren't missing anything. Even the best managed funds have significant fluctuations in performance from year to year.
Take a look at this Yahoo comparison chart of the two funds over 5 years and you'll see that they were neck and neck until early 2007.
http://finance.yahoo.com/q/bc?s=DODBX&t=5y&l=on&z=m&q=l&c=oakbx
That's when Dodge and Cox Balanced went into a swoon, performing in the bottom quartile.
Will it recover? I think so. D&C is a value oriented shop and value stocks, which include a lot of bank stocks, have been hard hit in the last year. Go back 10 years and you'll find that both funds were in the top 5 percent of moderate allocation funds.
Scott