I was just reading a piece here at the BF page, about how the Wizards gamble too much defensively by going for steals and switching too much. I agree with most of the points in it, but I think that you can't just look at it as a defensive problem, isolated like that, when the defensive schemes also relate to what our offense is trying to do.
We have precious few convincing ball handlers on this team and only a couple of players who can create their own offense (Wall, Nene). As a result, our half court offense is not very good at all. Our offensive weapons like Ariza, Webster and Beal all rely on others (Wall or Nene) to create opportunities for them. In order to make up for this, Wittman uses this kind of high pressure and high risk defense, to get the before mentioned players open looks from the fast break or a semi break. We all know what happens when Ariza starts to dribble, and Webster isn't all that much better at creating his own shot. Also, Gortat, Booker, Vesley and everybody else need somebody to help them along offensively.
The only way to get any kind of good offense out of most of our players is to keep getting them wide open shots or dunks, where they don't have to handle the ball too much. Wittman does this by running the break as much as possible and having Wall drive hard and dishing it out to our shooters.