In what way is the presidents effectiveness as chief economist dependent on his or her expertise as chief diplomat

The President's roles as chief economist and chief diplomat-related, in a way that both roles can have an effect on the United States' relationship with other countries.
The President is expected to have a keen eye on the nation's economy as a chief economist, every President is also a chief diplomat the main architect of American foreign policy and the nation's chief spokesman to the rest of the world.