PHOENIX -- In his first two big league starts, D-backs right-hander Ryne Nelson was dominant in throwing seven shutout innings against the Padres and then six scoreless frames against the Dodgers.

But it's never completely smooth sailing when a player is adjusting to the Major Leagues. On Sunday afternoon, while making his third start, Nelson had a couple of things working against him.

First, the Padres had just seen him two weeks before, so they knew what he featured. Second, he didn't have his best command.

• Box score

That, along with another quiet day by the Arizona offense, resulted in a 6-1 D-backs loss to the Padres. After winning the first game of the series, the D-backs dropped the next three to lose their fourth straight series.

In his first two starts, Nelson was aggressive early in counts with his fastball, jumping ahead of hitters. From the first inning this time around, though, he fell behind hitters. And it cost him.

"I thought Nellie was OK today," D-backs manager Torey Lovullo said. "He wasn't very fastball efficient. I think that was the difference between today's outing and the previous two. I think his fastball was being sprayed around a little bit. He made some middle-middle mistakes, and they made an adjustment to him.

“You could tell early on that he had trouble commanding [the fastball]. He started getting zoned in a little bit, but by that time there had been a couple of home runs off him. And we just couldn't get anything going offensively."

Nelson walked just two batters in his first two starts, and one of those was intentional. On Sunday, though he only allowed three hits, he walked four in 5 1/3 innings.

The first walk he issued was to the second batter of the game, Juan Soto, and Manny Machado made it hurt when he followed with a homer to give the Padres a 2-0 lead.

Nelson allowed a run in the third that was unearned because of his throwing error -- he tried to pick Jurickson Profar off first base. Soto touched him for a homer in the fifth.

"I definitely didn't have my best stuff," Nelson said. "I could have gotten ahead more, and I think I just was putting myself in holes and having to fight out of them -- didn't throw enough strikes, for sure. I didn’t really get ahead at all, and when you're fighting back and you're throwing in hitter's counts, good teams are going to do damage off of you."

Nelson's day came to an abrupt end when the first batter of the sixth, Brandon Drury, lined a ball off his right forearm.

Lovullo and athletic trainer Ryan Dipanfilo came out to check on Nelson, who said he felt OK, but Lovullo did not want to take any chances with the 24-year-old's health and removed him from the game.

The ball hit Nelson in the area of his flexor mass and X-rays taken were negative, so he should be fine to pitch the next time his spot rolls around.