PHOENIX (AP) -- Tyler Skaggs needs to work on his control - of his pitches and his emotions.
"For whatever reason, he had no command of his fastball," Arizona manager Kirk Gibson said after Skaggs and the Diamondbacks lost 12-3 to the San Diego Padres on Saturday night. "He was trying to throw the ball in and couldn't get it in there. He is obviously struggling. He gets guys on base and puts some pressure on. You can see by his mannerisms he feels it a little bit."
Skaggs' next opportunity to work on his command and his nerves will occur in the minors. After the game, the left-hander was optioned to Triple-A Reno.
"Up here you need to throw a fastball, you need to throw it for strikes and work it in and out," Skaggs said. "I haven't been doing that. I'm only 22, so I have a lot more starts ahead of me."
San Diego managed only three hits off Skaggs (2-3), but took advantage of the rookie's wildness to open an 8-1 lead after four innings.
With the game tied 1-1, Skaggs retired the first two batters he faced in the third. But he walked Chris Denorfia, hit Chase Headley with a pitch, walked Carlos Quentin to load the bases and then walked Jesus Guzman to force in Denorfia.
Yonder Alonso followed with a bases-clearing double into the right-field corner to give the Padres a 5-1 lead.
"The third inning, I had two quick outs then could not find the zone," Skaggs said. "I could not find the zone with any pitch. It's really tough. That's probably one of the hardest things to do in sports."
In the fourth, Skaggs walked Cashner with one out before giving up a two-run, two-out home run to Denorfia to make it 7-1.
Tony Sipp came on in relief, but Headley drove his first pitch into the left-field stands to stretch the lead to 8-1.
Skaggs allowed seven runs on three hits and five walks, hit a batter and struck out five over a career-worst 3 2-3 innings.
"He wants to be so perfect," Montero said. "He put too much pressure on himself. That is not going to help him. You have to relax a little bit. You have to make one pitch at a time and that is when you are going to get out of a jam. But if you try to make just one pitch and get three outs it is tough to do."
Skaggs' opposite number, San Diego starter Andrew Cashner, also walked five batters. But unlike Skaggs, he was able to escape a pair of jams with inning-ending double plays.
Cashner (7-5) allowed three runs on four hits, walked five and struck out five for his second straight win, both coming during San Diego's second consecutive 10-game road trip.
Cashner also hit his first career home run.
Denorfia and Headley added back-to-back home runs, Alonso drove in four runs and Quentin had three RBIs for the Padres, who have won two of their last three and four of six.
Paul Goldschmidt and Miguel Montero homered for the Diamondbacks, who had their two-game winning streak snapped.
San Diego took a 1-0 lead in the first when Denorfia walked and scored on Quentin's two-out double.
Arizona tied the game in the second on Montero's third home run in his past seven games.
Long after Skaggs had departed, Goldschmidt's one-out homer in the fifth, his 23rd, pulled Arizona within 8-3.
Cashner homered off Josh Collmenter with one out in the sixth, and Quentin and Alonso added RBI singles during San Diego's three-run ninth against David Hernandez.
NOTES: Skaggs has made 14 minor-league starts scattered around his four major league stints. . The Diamondbacks did not announce the corresponding move to replace Skaggs. . Alonso has nine RBIs in nine games since the All-Star Break. ... Skaggs had issued 10 total walks in 35 innings across his last six starts. ... Denorfia's nine home runs against Arizona are the most among active Padres. ... Denorfia and Headley were the fourth set of Padres to hit consecutive home runs this season. Nick Hundley and Will Venable hit back-to-back homers July 15 against San Francisco. ... Montero had missed the Diamondbacks' past three games with a stiff back. ... Arizona LHP Patrick Corbin (12-1, 2.31 ERA) will look to remain unbeaten at home when he takes on RHP Tyson Ross (1-4, 3.35) in the series finale. Corbin is 8-0 at Chase Field, the second-most home wins in the majors. Ross snapped a 12-game losing streak when he held the Brewers to two hits and two walks in the Padres' 6-2 win.
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