Andre Miller separated his right shoulder in Tuesday's win at Houston and immediately returned to Cleveland for tests, leaving the Cavs without their second-leading scorer and the league leader in assists.
Dirk Nowitzki played despite a sprained left ankle suffered Tuesday, but the Mavericks hardly needed him.
Finley made 10-of-17 shots and Hardaway sank 4-of-8 3-pointers as Dallas completed a season series sweep. Nowitzki finished with 15 points and nine rebounds in 32 minutes.
The Mavericks pulled away midway through the second quarter with a 16-6 run. Hardaway scored eight points during the burst, which gave Dallas a 39-28 lead.
Lamond Murray scored 11 of his 23 points in the third quarter as Cleveland pulled within eight, but got no closer.
Jumaine Jones had 13 points and 10 rebounds and Bimbo Coles added 13 points for the Cavaliers, who failed in a bid for their first three-game winning streak of the season.