Originally Posted by moon language
Because Roddick's success was built on his serve and the rest of his game was limited. Harrison lacks the serve but already has a lot of Roddick's negative traits (vulnerable backhand, too much reliance on defense, and too much of a willingness to embrace his temper). Harrison needs help developing his ground game.
Just cause he talks to him doesn't mean that they are talking about their games, Roddick just probably gives him advice.