Starling Marte and Neil Walker both drove in a pair of runs in the outburst, and Garret Jones also notched a pair of RBI for the Pirates, who won their second game in a row.
James McDonald (1-1) earned the win despite allowing four runs in the first inning. McDonald allowed four runs on four hits over five innings. Jason Grilli allowed a hit in the ninth but notched his third save.
Arizona led 4-1 after the first inning but Pittsburgh jumped ahead 6-1 with their fourth-inning outburst.
Brandon McCarthy (0-1) took the loss on six runs – four earned – off 10 hits in 6 2/3 innings.
Kate Middleton recycles dress at movie premiere
Jordana Brewster on Paul Walker: 'He was an enormous presence in my life'