Blache provided 20 points and 12 boards while Kris Humphries added 20 and nine to help the Nets battle back from a 17-point first-half deficit.
Tornike Shengelia supplied 11 points and 11 rebounds for Brooklyn, which holds the fourth seed in the Eastern Conference.
The Wizards, meanwhile, dropped a fifth straight despite 18 points, 12 assists and six rebounds from John Wall.
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