Hoffman, the former star closer, will evaluate and help coordinate all pitchers at Double-A, Triple-A and the big league team.
Byrnes says Hoffman "will be a key part of finishing the development of our younger pitchers."
Byrnes cited Hoffman's expertise, passion and communication skills as being critical for helping young players.
Hoffman had been a special assistant to the president and CEO the last three years following his retirement in January 2011.
Hoffman's 601 career saves, in 677 chances, are the second-most in major league history.