Bradley Johnson has an "Afro-American" grandfather, and though this has been hashed out before, he still believes he can play for the US team. Which this forum has concluded a few years ago is not possible, since you can't get US citizenship through one grandparent alone. In any case, sounds like he doesn't have a passport yet, and won't get one anytime soon. http://www.bbc.co.uk/sport/0/football/22219217
If his parent with the American bloodline resided in the United States before Johnson's birth, that would give him citizenship, right? But what exactly constitutes residence? Is it length of time, or something else?
Well, if one of Johnson's parents is a citizen and lived in the US for five years before his birth, including two years after age 14, then Johnson can obtain citizenship. For his grandparents to pass on citizenship to a parent in that way, one of them needs ten years residency in the US, at least five of which are after age 14. (The law changed in 86, Johnson was born in 87.)
https://www.bigsoccer.com/community/threads/bradley-johnson-at-leeds.1197424/page-4#post-19535514 Pretty sure we have a definitive "no" on this.