The festival, which includes a marathon, half-marathon, group relay, 5k and kids race, will stagger starting times between 7 a.m. and 8:45 a.m. on Oct. 18, the day the Orioles and Kansas City Royals would potentially play Game 7 of the American League Championship Series at Camden Yards.
The game -- which would not be played if either the Orioles or Royals first won four games in the best-of-seven series -- would begin at 8:07 p.m. Running festival organizers said the races' start times would stay as they are now even if the ALCS concludes before Oct. 18.
If the series goes at least six games, raceday changes would be more drastic.
Rather than running through Camden Yards on Eutaw Street -- the finish line is between Oriole Park and M&T Bank Stadium -- participants would be sent down the Russell Street access road. The course would also close at 1 p.m. to give crews time to ready the ballpark area for Game 7.
A series of at least six games would also force organizers to cancel parking and shuttle service for the race expo on Oct. 17. Though the expo will go on, organizers urged participants to pick up their race packets on Oct. 16 instead.
"Please understand we have to make some tough decisions," Corrigan wrote.
About 27,000 people participated in the running festival last year. Online registration for this year's festival closes on Oct. 12.