Ross retired nine of the final 10 batters he faced and overcome a rough beginning.
Ross, who six days ago had a complete-game victory over these same D-backs, struggled with his command, walking five of the first 11 batters.
"I just had trouble repeating my delivery and I was a little inconsistent with my release point," Ross said of his early struggles, ones that led to two runs in the third inning.
"They [D-backs] had a great, patient approach and I got myself into some trouble early on."
The D-backs took three of those five walks in that two-run third inning and Paul Goldschmidt made Ross pay with a full count, two-run single with two outs in the inning.
In between innings, Ross huddled with pitching coach Darren Balsley to work on remedying a few mechanical flaws.
"Darren gave me some good advice, I made an in-game adjustment and finished strong," Ross said. "He's got the time to come in and look at video and I trust him fully. He's got the perfect tip on what I need to do and get back on track.
"In-game, it's a word or two from Bals that gets me back on track."
Ross finished fast, striking out the side in the fourth inning and getting a big double-play ball to end the fifth. He retired all three hitters he faced in the sixth inning before turning the game over to the bullpen.
Ross allowed two hits, two runs, walked five and struck out seven. His ERA is now 3.57.
"He's a pro. He doesn't break down. He's tough. This kid is mentally tough. He is bright too. So, you got courageous and bright," Padres interim manager Pat Murphy said of Ross. "They work through those things. He knows if I want to stay out here and keep doing what I am doing -- I can't let this get the best of me."
• After the game, Murphy said that pitcher Josh Johnson -- attempting to come back from Tommy John surgery last year -- had an MRI done recently on his repaired ulnar collateral ligament that, because of the revision (surgery) was inconclusive. Murphy noted that Johnson will resume throwing soon. He had to stop a simulated game on June 15 because of tingling in the fingers on his right hand.