I'd like to add an other element to this equation. Affinity (of course). This clip sums it up for me: talent + effort + affinity = something special. Alan Alda describes the development of his very successful working relationship with Wayne Rodgers. They are known to many as Hawkeye Pierce and Trapper John MacIntyre from classic series M*A*S*H which lasted a decade for a reason. Click here for clip.
P.S. if you are not yet a fan of M*A*S*H and or Alan Alda I hope you become one.