Before the appearance of V, FlashForward was the new scifi darling of the season. In October, its adults 18-49 ratings seemed to have stabilized in the renewal-worthy 3.0/3.1 range, but its last two airings have fallen to a 2.7 (against the World Series) and a 2.6 rating (with no World Series).
If it doesn't recover from that 2.6 rating, its future on next season's schedule is in doubt. And if the ratings go lower than that, its got no future at all.
Edit: I just realized that the X axis isn't the episode airdates, but instead the final day of each week the episode aired. Sorry for the confusion.