My Credentials Would be Some Combination of the Following:
At least one major title
Participation in at least one Mosconi Cup
Qualifications as an instructor
A track record of dignity and sportsmanship
A track record of service to the game
I'll restirct my consideration of this topic those that have yet to captain an American Mosconi Cup team. I feel that the American captain should be a grand old man of the game, and, as Europe has demonstrated, instructors are worthy of consideration. My preference would be for someone who has contributed to the sport on multiple levels. Grady would certainly be a solid choice.
In the instructor category, a great choice would be Mark Wilson, one of the world's best instructors, a man of impeccable dignity and grace, and a man who competed in the Mosconi Cup as a player in the 1990's. Mark has frequently demonstrated his scholarship of the game as a commentator for pro events.
In the player category, a really solid choice for captain would be Tony Robles, the former BCA Open champion who has distinguished himself as a player and has been a member of a winning Mosconi Cup team. Tony is also very accomplished as an instructor. Best of all, though, Tony, in a vote conducted by his fellow pros, was named Sportsman of the Year on the PBT twice. He's got the knowledge, the dignity, and the respect of his peers that would make him a great choice. Tony is also a founder of the Predator Tour and the amateur league called the NAPL.