Cuz that's what they were doing. They have a potential NFL caliber quarterback, And even in the NFL it's a losing strategy most of the time to sit back and let him an elite quarterback stand in the pocket and pick you apart.
Even the greatest quarterback of all time, Tom Brady, doesn't like to get hit and doesn't like pressure. So against a decent quarterback, like Washington has, then no I don't believe sitting back the vast majority of the plays and thinking that he will make mistakes is a winning strategy. it's an effective strategy against bad quarterbacks, however but that's not what Washington has.