Baseball Prospectus's Clay Davenport used BP's Playoff Odds Report to determine the eight worst collapses in baseball history, measured by highest chance to make the playoffs after August 1 and subsequent failure to do so (in light of the Cleveland Indians' fall this year, the 8th worst). Unsurprisingly, the 1969 Chicago Cubs show up on the list, doing so at number 5. On August 7, the Cubs had a 98% of winning the NL East:

At 71-41, they had the best record in the National league, although the Orioles were better in the AL. They won the league 98.0% of the time in the simulations, but objective computer simulations, by their very nature, know nothing about Miracles. The Mets got hot and the Cubs went cold, so much so after the Mets swept a doubleheader from the Expos on Sept. 10 they took over the division lead both in record (84-57 to 84-59) and in chances (51.6%-47.8%). The Mets stayed hot, finishing the year on a 41-15 run that left the Cubs eight games behind at season's end. As the Braves and Orioles were to find out, the Mets' hot streak didn't end with the regular season.

(Hat tip: Baseball Crank.)