1995 Angels
The California Angels were on cruise control with a cushy 11-game lead over the Seattle Mariners in the AL West on August 9 of the 1995 season. The New York Yankees were a game ahead of Seattle for the lone Wild Card spot at the time.
By the time September rolled around, the Angels still held a 6.5 game lead. It wouldn’t be enough.
Not one, but two nine-game losing streaks caused California’s lead to vanish. Seattle stole the division lead away on September 22, nine days before the end of the regular season.
The Angels would manage a five-game winning streak to end the season to move back into a tie with Seattle, forcing a one-game playoff to determine the division winner. Unfortunately, they were shut down by Mariners ace Randy Johnson, who struck out 12 batters in a dominant 9-1 victory.
This scenario isn’t all that different from the one the Red Sox currently face. On September 6, the Angels had a 5.5 game lead in the division over Seattle. They were five games ahead of the Kansas City Royals, who held the Wild Card spot at the time, and six ahead of a Yankees team that would end up winning the Wild Card. The Mariners managed to climb over the Angels and Royals to make the playoffs despite a similar hole to the one Boston finds itself in now.