PHOENIX -- The Arizona Diamondbacks' pitching staff has made a steady climb under pitching coach Mike Butcher the last two seasons, so much so that they appear as prepared as any to withstand the loss of No. 4 starter Taijuan Walker.
After its 3-1 victory over San Francisco on Thursday, Arizona has a National League-low 2.87 ERA while tying a franchise record with a 13-5 start and setting a franchise record with six straight series victories to open the season.
Right-hander Matt Koch has the first claim on Walker's rotation start when he opposes San Diego right-hander Tyson Ross in the first game of a three-game home series against San Diego on Friday.
Koch will make his third major league start, his first since the final day of the 2016 season, while Ross has had a nice return to form after two injury-influenced seasons.
Patrick Corbin and Zack Godley have stepped up to join Zack Greinke and Robbie Ray to form a solid Arizona starting quartet. Corbin has a 1.65 ERA and an 0.70 WHIP with 37 strikeouts in 27 1/3 innings.
"Having had five good starting pitchers eases the sting," Arizona general manager Mike Hazen said after Walker was found to need season-ending Tommy John surgery.
"Yes, we are going to need to fill out the fifth spot of the rotation moving forward, but we feel very strongly on the other four days, the same as we always did. Having that depth in our rotation helps you to overcome that a little bit. Certainly, those two guys stepping up along with those guys at the top.
"Planning out one day in your rotation to try to figure out how you are going to put it together, how you are going to use the bullpen that day versus the other days, I think that allows you that freedom to maybe match up a little more, use your bullpen in a different way on that day. Use a different starter, depending on the matchup with the flexibility we have with optioning guys. All those things could come into play."
Koch was one of the last starters optioned to Triple-A Reno out of spring training, and Reno right-handers Braden Shipley and Troy Scribner also are options if the Diamondbacks opt to mix and match.
"We want stability," Arizona manager Torey Lovullo said. "To have a flimsy roster spot that you are bouncing around can be challenging for a young player. I don't want to predict what is going to happen. I just know that we are going to always try to find the best guys to help us win as many games as possible."
After winning the final three games of a four-game series against San Francisco, the Padres were swept by the Dodgers in a three-game series to conclude a seven-game homestand that ended Wednesday.
The Dodgers outscored the Padres 30-10, and only one San Diego start got into the fourth inning, a reversal of early form. The Padres have nine quality starts, and Tyson Ross and Joey Lucchesi have two apiece.
Ross is 2-1 with a 3.50 ERA in three starts after missing most of the last two seasons with arm issues. He won 13 games with a 2.81 ERA and 10 games with a 3.26 ERA in his last two healthy seasons with the Padres, in 2014-15. Luis Perdomo gave up seven earned runs in three innings Wednesday to bump his ERA to 8.36, and manager Andy Green talked about his future after the game.
"We've got to reevaluate the situation and what's best for us," Green said. "We've been talking about a competitive culture and we intend to give guys opportunities. We have a number of young guys we like in the organization. I'm sure the conversation will be forthcoming here soon as to what's our best move."
Rookie Lucchesi made the team out of spring training, and left-hander Eric Lauer is considered a top prospect.
The Padres struck out 13 times Wednesday and tied a franchise high with 20 strikeouts in a 12-inning loss on Tuesday, but offensive reinforcements are on the way. Corner outfielder Wil Myers (arm nerve) and center fielder Manny Margot (bruised ribs) could join the Padres in Phoenix this weekend.
Myers homered for Class A Lake Elsinore on Wednesday and could be activated Friday. Margot, who took a pitch to the ribs April 10 that led to the benches-clearing brawl with Colorado the next day, is eligible to be activated Saturday.
Ross has had success against Arizona, going 4-3 with a 2.65 ERA in 13 appearances, 12 starts. He threw a complete game against the Diamondbacks in 2015, when he was 2-0 with a 2.00 ERA in four starts. He has not faced them since.
Koch made the second of his two career starts against the Padres on the final day of the 2016 season, giving up one run and five hits in six innings. He did not get a decision. He pitched two scoreless innings of relief at St. Louis on April 7 after being recalled from Triple-A Reno when Jake Lamb was placed on the disabled list April 3. He was returned to Reno last week.