PHOENIX -- The D-backs suffered a pair of tough losses Saturday, one on the field and one off.

Before their game with the Brewers even started came word that right-hander Ryne Nelson, arguably the team's best starting pitcher the past few months, would need to go on the injured list with inflammation in his right shoulder.

Then, once the game got started, the Brewers pounded the D-backs, 15-8, making for a long night in front of a nearly packed house at Chase Field.

The good news for the D-backs is that Nelson's injury does not appear to be serious with manager Torey Lovullo expressing confidence that Nelson would not have to miss more than the required 15 days.

Because Nelson's placement on the IL is retroactive to Sept. 11, that could mean that he would be back in late September, which would give him a chance to make a start before the postseason begins.

That's important because should the D-backs make the postseason, they want Nelson to be one of their starters.

Overall this season, Nelson is 10-6 with a 4.33 ERA, but since July 1, he is 5-0 with a 3.16 ERA.

"We would not be where we are without Ryne Nelson and his ability to go out and help us win baseball games," Lovullo said. "You look at the statistics, it shows up as very positive. But what he's given us every start has been very consistent."

Until Nelson returns, the D-backs will need to replace him in the rotation. The most likely person to do that is Jordan Montgomery, who was removed from the rotation after Merrill Kelly returned from injury last month.

It's been a tough season for Montgomery, who remained unsigned throughout the offseason before the D-backs nabbed him around Opening Day on a one-year deal worth $25 million with a vesting option for 2025.

Montgomery had a 6.44 ERA in 19 starts before being moved to the bullpen.

Another pitcher who will need to help pick up the slack in Nelson's absence is Brandon Pfaadt, who struggled with his command in Saturday night's loss.

The Brewers scratched across a run against Pfaadt in the first, and after he retired the first two batters in the second, things spiraled out of control for him.

Pfaadt allowed the next seven batters to reach base with Willy Adames capping the inning with a grand slam that chased Pfaadt from the game and gave Milwaukee an 8-0 lead.

The Brewers piled on another four runs in the fourth, and they were in complete command after that even though the D-backs rallied for two runs in the sixth, two in the seventh and four in the eighth.

Pfaadt's past several starts have not been up to his usual standards, and it is important for the D-backs that he gets back on track, especially with Nelson out.

"Definitely not how we wanted it to go," Pfaadt said. "I think we know how important these games are, and to kind of let the team down with a game like that, I think is unacceptable, and we got to do better."

The D-backs will try to salvage the final game of the three-game set Sunday afternoon, and they will face the Brewers again from Thursday to Sunday for four games in Milwaukee.

"We've got to be better on the mound," Lovullo said. "That, for me, is really what it comes down to. Tonight was total lack of pitch execution -- missed pitches in the middle of the zone, lack of command with our secondary stuff. Just too many misses to a team that is just going to fight you the whole way and not give in."