Chacin vanquished the Padres in 74 pitches, including a startling 53 strikes. Through four innings, he had strikes on 31 of his 35 pitches.
"It wasn't a really good [pregame] bullpen -- I was throwing too many balls in the dirt, my changeup, my breaking ball," Chacin said. "But when I got to the game, I just let the ball go, like I have been doing, having fun."
It's time to put to an end the questions that swirled around Chacin (2-4) at the beginning of the season, when he was 0-3 with a 7.05 ERA.
Chacin, 24, was dogged by questions about his offseason conditioning and drew askance looks when he appeared to be having arm trouble in Spring Training.
But it turned out he had a nerve injury in his chest. In three starts since returning to action, after missing nearly four months, Chacin has posted a 1.50 ERA.
"I was really worried, because I didn't know what really happened to my arm," Chacin said. "I felt it in my biceps, shoulder. They never found anything right there, just inflammation.
"After they found out, I was more relaxed. I'm happy."
Now, manager Jim Tracy can return to his dreams of Chacin becoming dominant. Chacin appeared headed in that direction for the first 14 starts of last season, when he was 8-4 with a 2.81 ERA and was under legitimate All-Star Game consideration. But he battled forearm tightness for a brief period, and although he says the injury healed quickly, he struggled to an 11-14, 3.62 finish.
Now healthy and with command of his fastball, Chacin could finish the season making strides toward what the Rockies have expected all along.
"He's doing it with fastball command," Tracy said. "And his secondary pitches, which are very special, they don't get to see them quite as often as when he's trying to get back into counts when he's lacking fastball command."
Chacin has fashioned "quality starts" -- six or more innings, three or fewer earned runs -- in all four of his career starts against the Padres.
"That's as efficient as I've seen him," Padres manager Bud Black said.
Tyler Colvin homered -- his 16th -- to open the second against Padres starter Edinson Volquez (9-10) and doubled in two runs in a three-run fifth. Josh Rutledge had three hits and Jordan Pacheco extended his hitting streak to 10 games with a double as the Rockies (54-77) won for the 13th time in the last 19 games.
"It was like, 'OK, [Chacin] can definitely work with this; he can run with this,'" Rutledge said. "He had command of every pitch and kept pounding the zone."
The Rockies also experienced a couple of happy returns.
Jason Giambi, after missing 35 games with viral syndrome, blooped a pinch-hit, eighth-inning single to load the bases. Center fielder Dexter Fowler, in his first start after being limited to pinch-hit and reserve duty since suffering a right ankle sprain on Aug. 22, followed with his 13th homer of the season and first career grand slam, off Padres reliever Miles Mikolas.
The Padres (62-72), who lost for the second time in the last 12 games, had little chance against Chacin.
Chacin fanned leadoff man Everth Cabrera on three pitches -- the first of his four strikeouts -- and was done with his blink-and-he's-gone first inning in eight pitches.
Chacin gave up five hits, including Will Venable's leadoff homer in the sixth, and walked two. The only time he allowed multiple baserunners was in the second, when Yonder Alonzo and Cameron Maybin each singled with two outs. But Chacin worked Alexi Amarista into a fly ball to right.
It was the first time a Rockies pitcher had gone seven innings since June 4, when Christian Friedrich did it in a victory over the D-backs at Chase Field. Chacin also showed an extreme example of what could be possible under the Rockies' oft-discussed pitching plan.
Since late June, starters have been limited to around 75 pitches. One key is a history that shows elevated offensive numbers when a pitcher -- home or road -- faces a lineup for a third time at Coors.
But Chacin was so economical that Tracy let him go through the Padres' order a third time. He gave up two hits, including the homer, and a walk, but never found himself in trouble.
"You have to go get guys," Chacin said. "You can't be, 'I've got two strikes, I'm going to throw one here to set up for another pitch.' You have to throw strikes, make quality pitches down in the zone, make them swing and get outs quick."