You are also rewarded for finding 'rare' answers.
Furthermore, players who joined a new team this offseason don't count for that team, since they haven't appeared in a game for them (yet) DeAndre Hopkins wouldn't work for the Texans-Titans intersection above. So he'll only be a correct answer for those eight.
Players must have played a regular-season game for the team(s), so, for example, while Josh Johnson has been a member of 14 different NFL rosters, he's appeared in a regular-season game for 'only' eight. Bragging rights with your fellow sports fanatic friends is the most significant thing on the line. The game originally started with MLB - and my colleague Matt Snyder did an awesome job explaining the rules in-depth there - and now also includes NBA.