San Francisco manager Bob Melvin didn't mince words following his team's sixth straight loss Tuesday night, saying the Giants played a "terrible game" against the host Arizona Diamondbacks and looked like they were "running around in quicksand."

The Diamondbacks' Kevin Newman hit a two-run double off Giants starter Kyle Harrison in the third inning and Lourdes Gurriel Jr. had one of his own in Arizona's four-run seventh. Gabriel Moreno also finished with two RBIs and Blaze Alexander had three of the D-backs' 13 hits in their 8-5 victory over the slumping Giants.

San Francisco missed early opportunities against Diamondbacks starter Blake Walston, hitting into two inning-ending double plays and failing to score with the bases loaded and one out in the second inning.

"That was a terrible game by us today, especially the early portion of the game," Melvin said. "When you're going through losing streaks, at least you fight. For the most part we have. That was an awful game."

Pinch-hitter Mike Yastrzemski hit a three-run homer in the eighth inning but it was too late for the Giants, who have lost a season-high six straight.

"We made it interesting at the end but didn't play well," Melvin continued. "Made Harry get multiple outs. We had a starter on the ropes every inning, couldn't cash in. It's a bad game and a bad stretch by us."

The left-handed Harrison, who allowed four runs (three earned) and eight hits over six innings, spent the early part of his start against the Diamondbacks watching balls go off his teammate's gloves.

Arizona scored its first run in the third inning on a double by Alexander that skipped off shortstop Casey Schmitt's mitt. The next two came on Newman's double off third baseman Matt Chapman's glove and Moreno followed with a sacrifice fly.

Those were ruled hits, but a fielding error by Schmitt in the next inning set up Alexander's run-scoring single that put the Diamondbacks up 4-1.

"We just looked like we were running around in quicksand for a while," Melvin said.

When asked if any of his message was relayed to the team, Melvin answered, "I'm not going to talk about what I say to anybody."

The Associated Press contributed to this report.