Paul Goldschmidt, Marte and John Ryan Murphy collected two hits apiece for the Diamondbacks, who have scored 51 runs during a five-game winning streak. Goldschmidt, who extended his hitting streak to eight games, has hit safely in 13 of 14 to raise his batting average from .201 to .258.
Marte hit his NL-leading seventh triple.
Jay, acquired Thursday from the Kansas City Royals, was 0-for-12 in his first four games with the Diamondbacks before Tuesday, when he singled twice and hit a three-run homer in the seventh inning to conclude the scoring.
Starling Marte hit a three-run homer, and Josh Bell and Josh Harrison had three hits and an RBI apiece for Pittsburgh. The Pirates, who fell 9-5 on Monday in the opener of a three-game set, lost their eighth straight series and are 6-18 since reaching a season-high nine games over .500 in mid-May.
The teams combined for four errors and nine unearned runs, and neither starter made it into the fifth inning. Fernando Salas (4-4), the third of five Arizona pitchers, pitched 1 1/3 innings for the victory.
The Pirates trailed 8-0 after three innings but closed within 8-6 in the fourth and 10-8 in the seventh before Jay's second homer of the season put the game away.
Jay and Goldschmidt singled to open the six-run first inning before first baseman Bell fielded Jake Lamb's grounder and threw wildly to second base in an attempt to get a forceout. Jay scored, and Murphy singled home Goldschmidt for a 2-0 lead.
With two outs, Ketel Marte tripled to right-center field to drive in two runs. Jarrod Dyson was intentionally walked, and both runners scored when Pittsburgh starter Trevor Williams (5-4) made an errant pickoff throw to first base and second baseman Harrison threw wildly past third after retrieving the ball. Five of those six runs were unearned.
The Pirates got six runs back in the fourth to cut their deficit to two. Starling Marte's three-run homer capped an inning that included a double by Elias Diaz, a single by Bell, a hit batter, a walk and a catcher's interference. Four of the runs were unearned.
Daniel Descalso had a two-run single in the fourth inning to give Arizona a 10-6 lead. Gregory Polanco drove in a run on a groundout to make it 10-7 in the fifth, and Bell doubled home a run in the seventh.
--Field Level Media