Possible Clues:

• Oct. contest whose winner goes to the World Series
• Baseball semifinals, for short
• MLB best-of-seven series
• Oct. baseball semifinal
• World Series lead-in: Abbr
• Oct. pennant race
• Fall semifinal
• Oct. contest for a pennant
• Qualifier that the K.C. Royals won in '15
• L.A. lost it to Chi. in 2005