Possible Clues:

• Situation with a winner and loser ... and a description of 17-, 26- and 52-Across?
• Contest that's equally balanced; 0-0 match?
• Event where gains are balanced by losses
• *I win/you lose situation
• Where gains are equally balanced by losses (and a clue to this puzzle's theme)
• Concept in economic theory
• Balancing act?