Like I said, they've not been playing well but have gotten by with a light schedule and luck in close games until recently.
They were 9-4 in <2 run games from August 12 - Sept 1. Since then they've been 1-5, so 10-9 overall. Luck is evening out. 8 of those 19 close games came against the White Sox, Royals and Tigers, 3 of the worst teams the league.
As I said earlier they haven't played badly the entire month, they've had good stretches (like against SF), but collectively they have not been playing their best baseball.