PHOENIX -- D-backs right-hander Luke Weaver took another big step in his development Tuesday night.

In a 6-2 loss to the Pirates at Chase Field, Weaver clearly did not have the usual sharp command with his fastball, nor did it have the same velocity.

Still, the right-hander found a way to last six innings and allow just three runs. It wasn’t great, but it also could have been enough to still lead to a win had the Arizona offense figured out a way to solve Joe Musgrove.

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“You learn a lot about a pitcher and about a person, what they go through when stuff doesn’t go their way all the time,” D-backs catcher Carson Kelly said. “Little adversity and I think he did a great job and continued to battle through it.”

Given his success this year, it’s easy to forget that, at 25 years of age, Weaver is still learning his craft.

After a rough first start against the Dodgers, Weaver had been on quite a roll. In his five starts prior to Tuesday, he had compiled a 1.82 ERA.

From almost the first pitch of the game, though, it was clear Weaver wasn’t sharp. The Pirates had at least one runner in scoring position against him in four of the six innings he pitched.

Between his lack of fastball command and the way the Pittsburgh hitters attacked him, it was a perfect storm.

“They were aggressive early in counts,” Weaver said. “When you’re not throwing fastballs right where you need to throw them, those quick outs are turning into zero-out singles, so you’re in the stretch a lot, you’re trying to get some ground balls.”

Still, Weaver was able to pitch out of a lot of those jams in large part because he held the Pirates hitless in six at-bats with runners in scoring position.

Weaver might have gotten out of the evening having allowed just the one run if it were not for a poorly located 0-2 fastball to Josh Bell with two outs and one on in the fifth that Bell hit into the camera well above the batter’s eye in center for the first of two homers on the night.

Bell came into the game riding a 13-game hitting streak and hitting .415 with four homers and a 1.248 OPS over that stretch.

“I made just an absolute terrible pitch to Bell,” Weaver said. “A guy swinging a bat that hot, you just can’t make a mistake like that, especially when you’re in such an advantage count. I think it was 0-2. Not at all trying to throw it there. I just got on top of it a little too much and it just drifted on the plate. That was a stinger.”

Last year during his struggles with the Cardinals, Weaver allowed innings, and therefore outings, to spiral away from him. This year, for the most part, he’s figured out how to slow things down.

Now, it appears, he’s added the ability to compete with less than his best stuff.

That’s a good sign for his future -- and that’s important for the D-backs -- as he was a key piece in the trade that sent Paul Goldschmidt to St. Louis this winter. Weaver, the team hopes, will become a mainstay in the rotation.

“It’s one of those games where you grind,” Weaver said. “You’re not going to have your best stuff. But those are the games you can build off of and feel good about. I felt good about tonight. It could have been way worse the way I felt, the way the ball was coming out. You’re just trying to salvage and maintain and get deep into the game as well as I can.”