SAN FRANCISCO -- The Arizona Diamondbacks lost seven of their first 10 games this season, leading to grumbling about the high-priced signing of free agent pitcher Zack Greinke.

A week later, the Diamondbacks are winners of five straight and seven of eight after completing a four-game sweep of the San Francisco Giants to move one game above .500 (9-8) for the first time this season.

Paul Goldschmidt had two hits and two RBIs, Yasmany Tomas hit his third home run of the season and reliever Tyler Wagner pitched five scoreless innings for his first career win as Arizona beat San Francisco 6-2 Thursday afternoon.

On Wednesday, Greinke got his first win for Arizona, outdueling Giants ace Madison Bumgarner.

"It's not easy to sweep anybody in four games at the major league level, especially a team like that in this ballpark," Diamondbacks manager Chip Hale said. "I'm very proud of our guys, they battled. Today wasn't easy. Obviously, Shelby (Miller, the Arizona starter,) struggled early to throw strikes and just got picked up really, really big time by Tyler Wagner, so I'm really excited for our guys."

Miller was knocked out after two-plus innings, and he was charged with two runs on one hit and five walks. He threw 55 pitches, only 23 for strikes. In the third, Miller walked the only four batters he faced to force in a run.

Wagner came in with no outs and the bases loaded. He got Brandon Belt to ground into a run-scoring double play, then induced a groundout from Brandon Crawford to end the inning.

"I'm just trying to limit things, minimize the damage," Wagner said. "My job is to go out there and I'm obviously in the long-relief role so to get a ground-ball double play is what I was trying to do. Today, everything was working, sinker, cutter and changeup, working with (catcher Chris) Herrmann and mixing things up."

Miller said, "I felt like mechanically was just off. I'd have a couple of good innings here and there, and things fell out of whack for me in the third. I felt like I couldn't get the ball in the strike zone, and (I) beat myself there."

Giants pitcher Johnny Cueto (3-1) gave up eight hits and three runs while striking out three in seven innings. Getting only two runs of support, he fell short in his bid for his 100th career victory.

"I have plenty of confidence in my offense," Cueto said through an interpreter. "I mean, it's part of the game and I feel that eventually they'll turn it around."

Leading 3-2 in the ninth inning, Arizona added three runs to put the game out of reach.

With one out, Chris Owings singled and Herrmann walked, and they executed a double steal.

Pinch hitter Rickie Weeks Jr. hit a grounder to third, and Giants third baseman Matt Duffy elected to throw home. The throw beat the runner, but catcher Trevor Brown couldn't hold onto the ball and couldn't see that it trickled just to the right of home plate in foul territory. That allowed Weeks to advance to second and Herrmann to third.

Hot-hitting Jean Segura followed with his third hit of the game, a triple off the right field wall, to score Herrmann and Weeks.

In the bottom of the ninth, the Giants wasted a leadoff walk to Crawford when Angel Pagan grounded into a double play and Duffy grounded to short, ending the game.

"Overall, we can put together better at-bats from what we're used to doing, compared to what we're capable of as a team," Duffy said. "Maybe it's a little frustrating, but I don't think we capitalized on our opportunities."

After the Giants' two third-inning runs tied the game 2-2, Arizona retook the lead in the fourth on a ball that Tomas crushed to deep left-center, estimated at 410 feet.

The Diamondbacks got the game off to a promising start. Segura led off with a single to right. With one out, Goldschmidt doubled down the left field line, bringing home Segura.

Goldschmidt's RBI single in the third gave Arizona a 2-0 lead.

The Giants wound up losing their five straight and falling for the eighth time in nine games.

"It's early, we're in April but you hate to have a series like this, particularly (against) a team in our division and here at home," Giants manager Bruce Bochy said. "That's what's a little disheartening, but a lot of baseball left, and it's too early for them hopefully to be pressing. ... We just have some cold hitters right now."

NOTES: RHP Johnny Cueto was the ninth pitcher in Giants history to win each of his first three games with the team before losing Thursday. He was seeking to become the 12th Dominican-born player to reach 100 career wins. ... Previously, the Giants were swept only once at home in a four-game series at AT&T Park (since 2000), by the Cincinnati Reds in June 2014. ... Diamondbacks SS Jean Segura is batting .338 (23-for-68) in the leadoff spot with 10 runs, three doubles, two triples, three home runs and 10 RBIs.