PHOENIX -- Manager Bob Melvin didn’t mince words after the Giants’ losing streak reached six games with an 8-5 loss to the D-backs on Tuesday night at Chase Field.

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

The Giants’ undoing started in the third inning, which opened with two hard hits off lefty Kyle Harrison that got by shortstop Casey Schmitt -- a Jake McCarthy single and a Blaze Alexander double. Neither was ruled an error, but Schmitt said they were plays that should have been made.

“I think I should have definitely gotten those,” he said. “Just unacceptable on my part, so I just have to be better.”

Schmitt played more third base than short coming up in the Minors, but he’s been forced into the secondary position with shortstops Nick Ahmed and top prospect Marco Luciano on the injured list.

“I’m not going to use that as an excuse at all,” Schmitt said. “I need to make those plays.”

The D-backs took advantage, scoring three runs in the frame to take a 3-0 lead, but Harrison regrouped to allow four runs (three earned) on eight hits and no walks in six innings, striking out five.

“I just tried to compete and stay in the game as long as I could, give these guys a chance,” he said. “But just a tough, tough day. We got to clean it up.”

Harrison, who turned in a career-best seven scoreless innings at Coors Field on May 7, has allowed at least three earned runs in all five of his starts since. But he felt like he may have turned a corner on Tuesday.

“It was a good step forward for me today,” he said. “Velo was there, felt good. Changeup was there, slider was there. Good one to build on. Let’s get these guys tomorrow.”

Given a chance to get back in the game, the Giants’ offense simply couldn’t come through, going 2-for-10 with runners in scoring position. They’ve struggled to score since an 8-4 win over the Phillies on May 27, plating 18 runs during this six-game skid.

“We made them work and we got into situations where we’re in the driver’s seat, but then we let them off the hook,” Melvin said. “So that at-bat qualities were good leading up until we really needed a good at-bat.”

The D-backs pulled away against right-hander Luke Jackson, who inherited a 4-2 game in the seventh inning but couldn’t keep it close. Jackson was coming off a solid May that saw him allow five earned runs in 14 1/3 innings, but on Tuesday, he gave up four runs while only recording two outs.

“It just wasn’t a good day for him,” Melvin said. “He’s been finding his way, feels like he’s found his way a little with some games, but today was not a good one. A couple of walks and then it got out of hand.”

Mike Yastrzemski hit a three-run pinch-hit homer in the eighth inning, but it was too little, too late.

“We get their closer in the game, not that that’s any small win,” Melvin said, “but if we play any better earlier in the game, then it’s a game we can win even though it looked like it was out of hand.”

Matt Chapman continues to be the exception to the Giants’ struggling offense. The third baseman went 2-for-4 to extend his on-base streak to 22 games. He’s hitting .309 with 20 runs scored, 10 doubles, four homers and 14 RBIs since the stretch began on May 11, but his teammates have struggled to follow his lead.

“We looked like we were running around in quicksand for a while,” Melvin said. “It is what it is, but it doesn’t feel very good when you play like that.”

Does Melvin expect his club to respond to such a flat performance?

“Yeah, tomorrow,” he said. “We better.”