Though Pacheco was 3-for-4 on the day, his fourth inning shot passed by the green as the Rockies surged past Miami for good. Marlins starting pitcher Josh Johnson held them hitless for three innings, but Pacheco got the best of the Marlins ace and Opening Day starter.
"I don't know if it was a good pitch to swing at, but I put a good swing on it," Pacheco said. "Luckily it got out."
The three-run inning started with fellow-rookie Josh Rutledge legging out an infield single, then scoring from first on Fowler's troublesome double down the left-field line. Fowler stole third, but was nearly stranded as the next two Rockies batters flew to shallow right and popped to third before Pacheco lofted his two-run shot into the left-field stands.
"He's got a good swing," Marlins manager Ozzie Guillen said of Pacheco. "You put a good swing in this park, you're going to have a chance to produce. I don't think this kid wants to do much with the ball. Whatever pitch it is, he tries to put a good swing on the ball, and he did it for the home run."
The Marlins got on the board early thanks to a rally that started when an errant throw from Rutledge at short pulled Tyler Colvin off the bag at first. Despite the bad throw, replays appeared to show Colvin kept his foot on the bag long enough to get Emilio Bonifacio out.
It was one of at least four calls on the bases that video replays suggest were poorly called by the umpiring staff. Three of the calls went against the Rockies.
"They were a few questionable calls today, one of which cost us a run in the first inning on the very first play of the game, but that's all I'll say about that," manager Jim Tracy said.
Justin Ruggiano followed Bonifiacio with a double to center, and Carlos Lee's grounder to third plated Bonifacio.
Rockies starting pitcher Drew Pomeranz made it through four innings with his only other blemish being a solo homer to John Buck that opened Pomeranz's final inning and gave the Marlins a 2-0 lead.
"Drew Pomeranz battled," Tracy said. "He did not have good command. He was pretty much today throwing strikes with his fastball and fastball only. He did get some balls in on some guys."
Miami staged its last big threat in the fifth, with a leadoff single from Ruggiano followed by a two-base error from Rutledge, who was chasing down a shallow fly in left and ran into Andrew Brown's glove, stripping the ball from it to put runners on second and third with nobody out.
"Piggyback" reliever Adam Ottavino got Lee on a comebacker to the mound, intentionally walked Giancarlo Stanton, then struck out Donnie Murphy and retired Buck on a grounder to short to escape unscathed.
"I'm just thinking about the next pitch," Ottavino said of his approach under pressure. "I'm not going to change it just because I'm in a situation. Make my pitches, and that's my best chance of getting out of it. Once I got the first out on the first pitch, I knew we were going to walk [Stanton], so then I'm looking for a double play. I got ahead of [Murphy], so it changes with each pitch. Now I need a strikeout. Make the adjustment."
The Rockies tried to add insurance runs in the seventh, loading the bases through a leadoff walk, a double through the third baseman by Brown, and a two-out intentional walk of Fowler, but cleanup hitter Ramon Hernandez grounded to the pitcher to end the inning.
Matt Belisle contributed to the bullpen's run of 13 consecutive scoreless innings, dating back to the seventh inning Friday and including five each on Saturday and Sunday, with a nine-pitch eighth to retire the side in order.
"You can't do it any better than that that," Tracy said of Belisle. "That may have been some of his better stuff. Efficient to say the least. But stuff-wise, his slider today was as good as we've seen it all year. He was just pounding the strike zone, and not using much of the plate either."
Colorado loaded the based again in the eighth on another leadoff walk, a single to center from Pacheco, and a one-out blooper between the pitcher's mound and second base from Jonathan Herrera that fell for an infield single. Pinch-hitter Chris Nelson lined a ball to short that Jose Reyes knocked down and converted into a 6-5-2 double play, catching Pacheco at third and Tyler Colvin at home, both of whom had to hold up when Reyes nearly caught the hard liner. The Colvin call at home was the fourth of the questionable umpiring calls.
Colorado lost two key men in the last two days as Carlos Gonzalez went on the bereavement list and Michael Cuddyer went back on the disabled list two days after coming off it. They lost two more during the game as Eric Young Jr. left with a left intercostal muscle (rib cage) strain after his first-inning at-bat, and Rutledge was pinch-hit for in the fifth due to his left quad tightness.
The win gave Colorado a series split and a 5-2 record on the homestand.