Possible Clues:

• MLB semifinal
• World Series lead-in: Abbr
• Oct. 2017 Dodgers-Cubs matchup
• MLB playoff round
• World Series prelude: Abbr.
• It puts a team in the World Series (Abbr.)
• Best-of-seven qualifier for the World Series: abbr.
• The last thing the Colorado Rockies won in 2007: Abbr.
• Pre-World Series event, for short
• The Col. Rockies won it in 2007