The Nets took a 15-point lead on Blatche's 3-pointer and then endured a long scoring drought to end the game.
Brooklyn finished the regular season with a 49-33 record and wound up as the No. 4 seed in the Eastern Conference. The Nets, completing their first campaign in their new home after moving from New Jersey, will host Chicago in their playoff opener.
Brook Lopez led the Nets with 20 points and Blatche had 15, hitting 6-of-9 from the floor. Brooklyn closed out the season by winning six of seven.
Detroit, which closed out a 29-53 campaign, was led by 23 points from Will Bynum. The Pistons missed a chance to win their fifth straight, which would have been their longest such streak of the season.