In general, according to scientists, babyfacedness in men is a sign of lower testosterone levels, since testosterone ages men and makes them look more mature.  
 
Although the idea that babyfaced men are more successful, may have some validity; I mean, how else is Leonardo DiCaprio successful, and he's supposed to have a really domineering personality (dating models, starting fights, etc.).  
 
Hell, the success of East-Asians in all endeavors, including athletics, may be proof of the success of babyfaced men. Asians usually look more babyfaced compared to other races.