Alex White came in to relieve Pomeranz in the role created to follow the abbreviated starts of Rockies pitchers working under a 75-pitch limit. White and Pomeranz were both acquired last season in the Ubaldo Jimenez trade and have won a combined three games in 39 starts this season.
Since both have started throughout their professional careers, it was the first time the duo appeared in the same game.
White (2-9) threw 1 1/3 innings of relief, allowing five runs on five hits and three walks, one intentional, adding up to nine runs from the starter and long man in less than five innings.
It was White's first relief appearance since his first year in professional baseball, when he came out of the bullpen once.
"It's going to take some adjusting," White said of the new role. "I probably needed a little more time to get ready tonight, but I felt good once I got out there. That was my first time out of the 'pen. It can't get much worse, so hopefully it'll get better."
The hope, under the 75-pitch limit the Rockies have used in the latter part of the season, was to get five innings out of the starter, ideally working through the order twice. Pomeranz exceeded his limit and went twice around the order by the end of three innings, due to a lack of command.
"He ends up with almost a 30-pitch [first] inning and he does some more of it in the second inning, and some more of it in the third inning, and it's a little bit over 80 pitches in three innings," Tracy said. "That's not Major League pitching. It's that simple. Eighty pitches in three innings is not going to get you very far. Where it's going to get you is, with a 25-man roster, it's going to get a bullpen torn to pieces."
Pomeranz had a shining moment in May when he notched his lone win, throwing 6 1//3 shutout innings in Washington to claim a victory against Stephen Strasburg. But he's gone from a 3.06 ERA before the All-Star break to a 6.52 mark since then.
"I think I'm trying to do too much out there, trying to think about making too good a pitch, instead of just making pitches," Pomeranz said. "I'm trying to make every pitch perfect instead of throwing a strike or hitting a corner."
Arizona took the lead from Pomeranz with a three-run third, highlighted by a two-run double by Miguel Montero after a pair of walks to open the inning.
"As things started to unfold there, or I should say unravel, I'm sure there was a lot of thought process going on," Tracy said, noting that Pomeranz's tempo slowed as he faltered.
With the exception of the second inning, when Arizona loaded the bases and failed to score, the D-backs scored in every inning.
"Every guy we brought in [had trouble]," Tracy said. "You can't pitch like that, and we've seen our fair share of it."
After the Rockies tied it at 4-4 in the bottom of the third, White's four-run fourth, powered by four hits and two walks, gave the D-backs more than enough high-altitude breathing room.
Colorado got productive nights at the plate from Wilin Rosario (3-for-5), Chris Nelson (2-for-3) and Jonathan Herrera (2-for-4), who each drove in a run, and the young lineup showed encouraging maturity with key situational hitting early in the game against D-backs starter Wade Miley, making productive outs to move runners over and bring them in.
"[Miley] just left some pitches up and they've got some guys who have been swinging the bat and have been very hot too, and you have to give them some credit," D-backs manager Kirk Gibson said.
But not all of the Rockies' 12 hits were timely. The Rockies left eight on base and went 3-for-15 with runners in scoring position.