There are several reasons for this, each of them as flimsy as the last, but for fantasy football purposes, what's done is done. Griffin can be safely dropped in redraft leagues, and Cousins has three favorable matchups versus the Atlanta Falcons, Dallas Cowboys and New York Giants to close out the season.
Cousins has started one regular season game and appeared in five, including mop-up duty versus the Denver Broncos and the Kansas City Chiefs last Sunday. In his only career start, Cousins completed 26-of-37 passes for 329 yards, two touchdowns and one interception versus a then-flimsy Cleveland Browns defense.
Fantasy Spin: That lone start was the high point of Cousins' career thus far, as he's struggled during his relief appearances, albeit versus stiff competition. Despite that, the 2013 Atlanta Falcons defense is closer in similarity to the 2012 Browns than the 2013 Chiefs or Broncos, and there is room for Cousins to succeed in this matchup. On the season, the Falcons have allowed 3,195 passing yards, 25 touchdowns and seven interceptions to opposing quarterbacks, and also the ninth-most fantasy points to the position.
There's no question that Cousins is walking from the bench and into a dream matchup this week, but odds are that fantasy owners have gotten this far into the season with a stable option at quarterback. Cousins remains a high-upside QB2, but should remain benched in standard formats across the board.