On shots at the rim, teams typically allow a percentage of .657. The Wizards rank 29th, allowing .746.
On shots 3-10 feet, teams typically allow a percentage of .417. The Wizards rank 30th, allowing .547.

On shots 10-16 feet, teams typically allow a percentage of .427. The Wizards rank 29th, allowing .487.
On 2PT shots 16-22 feet, teams typically allow a percentage of .421. The Wizards rank 19th, allowing .438.
On 3's, teams typically allow a percentage of .365. The Wizards are 21st, allowing .377.
One can really see what an impact a true rim protector could make on this club. If we had an above average shot blocker at the rim who could force opponents to shoot at a league average efficiency at the rim and from 3-10 feet (with all other defensive metrics remaining the same: rebounds, steals, etc.), our defense would improve by about 7 points per 100 possessions. If that rim protector also managed to reduce our FTA's allowed to league average, the defense would improve by another 5 points.
I don't know if it's realistic to expect that one rim protecting center can have this kind of effect on all shots at the rim, but it at least illustrates the rather specific nature of our defensive problems. We're doing everything right except we're yielding an incredibly high FG% at or near the rim. Fix that, and our defense goes from awful to great. A 7-point improvement on defense would improve our defense from 26th to 8th. A 9 point improvement gets us to 2nd.