Phoenix, AZ (SportsNetwork.com) - Francisco Liriano overcame command issues to toss 6 1/3 scoreless innings and the Pittsburgh Pirates completed a three-game sweep with a 8-0 win over the Arizona Diamondbacks.

Liriano (1-1) walked six batters, but gave up just two hits, struck out seven and did not allow a runner past second base. He has recorded at least seven strikeouts in all four of his starts this season.

Pedro Alvarez and Neil Walker drove in two runs apiece and Gregory Polanco scored three times to back Liriano.

"That's the hitter I try to be," said Walker. "To have a series like this, it's a good sign for where my swing is at."

Alvarez produced what ended up being the deciding runs in the top of the first inning, which Josh Harrison started with a single to left. Polanco followed with a single and Andrew McCutchen walked to load the bases with no outs.

Jeremy Hellickson (1-3) retired the next two batters he faced, but Alvarez slapped a single to right to score two.

Consecutive singles from Polanco and McCutchen set up Walker's one-out double in the fifth inning that made it 4-0. Hellickson departed later that inning, and Andrew Chafin struck out Alvarez to strand Walker.

Hellickson was charged with four runs on seven hits over 4 2/3 innings.

"When he gets in trouble, he doesn't control the count," said D-backs manager Chip Hale. "When you fall behind good hitters, they're going to get you."

Chris Stewart padded the lead with a sacrifice fly to left in the eighth inning, and Pittsburgh tacked on three more insurance runs in the ninth to put the game out of reach.

Harrison and Polanco hit consecutive doubles to start the frame and make it 6-0. McCutchen plated Polanco with a sacrifice fly, and Walker scored later in the inning on Sean Rodriguez's single to right.

Game Notes

Polanco and Walker had three hits apiece. Pittsburgh outhit Arizona 14-3 ... The Pirates are 8-2 in their last 10 games.