SAN DIEGO (AP) Luis Perdomo was one of four players obtained by the San Diego Padres during the Rule 5 draft in December, and by all rights, he should be pitching in Double-A this season.

But this is a rebuilding year for San Diego, and so there Perdomo was Sunday night, taking James Shields' spot a day after the veteran right-hander was traded to the Chicago White Sox.

Perdomo and the Padres lost 10-3 to the Colorado Rockies, with the rookie giving up two-run homers to Carlos Gonzalez and Nolan Arenado.

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In his second start and 16th appearance for the Padres, Perdomo allowed six runs and eight hits in 4 1/3 innings, struck out three and walked one.

''He is on the verge of figuring it out,'' manager Andy Green said. ''He mostly got hurt on his off-speed pitches. His mistakes are middle of the plate, right where the hitter is looking for it. But there is more than enough that makes you think he has a chance to be special someday.''

Perdomo is the only one of those four Rule 5 draft picks on the 25-man roster.

''In an ideal world, he's learning in Double-A right now,'' Green said.

Gonzalez hit two two-run homers and drove in five runs and Jon Gray struck out a career-high 12 for the Rockies, who snapped a four-game losing streak.

Both of Gonzalez's shots were to center field. His first, in the first inning, was estimated at 444 feet, and his second, in the ninth, went 409 feet. He has 13 on the season and eight in his past 10 games.

Arenado had three hits, missing the cycle by a triple, and reached base five times. He was hit on the left elbow by a pitch from Brandon Maurer in the ninth inning.

Arenado was aboard for both of Gonzalez's homers.

Arenado extended his NL lead with his 18th homer, a line shot to left with one out in the fifth. Trevor Story was aboard on a double.

Gray (4-2) struck out the first five batters, becoming the second Rockies pitcher to do so. Bruce Ruffin did it on June 13, 1993, against Houston. Gray is the first to do it in the majors this season.

Gray's previous career high was 11 strikeouts, also against the Padres on May 2 at Petco Park. He allowed two runs and five hits in seven innings and walked one.

Gray allowed Wil Myers' RBI double in the fourth and solo homer in the sixth, his 10th.

''He mixed his pitches really well,'' Myers said. ''I was lucky enough to get ahead of him on the home run. But he was tough.''

San Diego's Brett Wallace homered with one out in the ninth, his third.

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