"I threw the ball all right, but that one crooked number did us in," Dempster said. "I prepared well enough, but I could've done a better job."
The end of a 2-4 road trip returned the Cubs to the .500 level (10-10), while also returning them to Chicago, where on Thursday they will kick off a six-game Wrigley Field stand with the first of four against the Florida Marlins.
This series was par for the Cubs' early-season course, 7-2 and 10-0 losses in which they collected a total of five hits sandwiching their own 11-3 romp in the middle game.
"We're beginning to find out those other teams want to kick our butts," Cubs manager Lou Piniella said of his two-time-defending National League Central champs being in the opposition's bull's-eye. "You're not going to win without playing with intensity every day, and the quicker that sinks in, the better."
While his manager dealt with intensity, Dempster sensed frustration.
"We know we're a better team than how we've been playing," the right-hander said. "Because of the talent we have, at some point we have to start playing good baseball."
On Wednesday, the Cubs' frustration was personified by reliever Kevin Gregg, who on his way out of the game in the eighth inning paused to critique home-plate umpire Jeff Kellogg's calls.
Carlos Marmol and Gregg combined to issue seven walks in one inning, three with the bases loaded, and after being removed with two outs in the eighth, Gregg briefly got into Kellogg's face while demonstratively gesturing toward the plate.
Asked later whether he felt he had gotten squeezed, Gregg said, "You all saw the game."
As such, the Cubs had more of a retort for Kellogg's work than for that of Arizona starter Doug Davis.
Davis (2-3) blanked the Cubs on two hits for seven innings, meaning this game was decided within the D-backs' first four batters, all of whom reached base. The key blow of the three-run first was Chad Tracy's RBI double to right-center, with Mark Reynolds' bunt single and Eric Byrnes' fielder's-choice grounder also delivering runs.
"After that, Dempster pitched pretty well," Piniella said. "He settled down and gave us a chance to get back into it.
"After Tuesday, I expected this team to jump out there and put some runs on the board. I expected us to go and hit [Davis] better than we did."
Not even lineup reinforcements helped toward that, with all but third baseman Aramis Ramirez back at work.
But first baseman Derrek Lee went 0-for-3 in his return, Milton Bradley was also 0-for-3 the day after his two-hit return and catcher Geovany Soto, after a one-day hiatus, went 0-for-3 as well.
Marmol's return, however, was the most pot-marked of all. Making his first appearance since suffering a knee injury on Friday, Marmol walked four of the five men he faced, two with the bases loaded.
"He needed some work," Piniella said, "and he will be better because of this."
Tracy's leadoff homer in the third made it 4-0.
Following that home run, both starters entered dominant mode. Between them, Dempster and Davis retired 23 of the ensuing 28 batters, each allowing only one hit in that span (singles by Arizona's Justin Upton in the sixth and the Cubs' Aaron Miles in the seventh).
Dempster (1-1) departed after issuing a leadoff walk in the seventh to Ryan Roberts, who was batting for Davis. In dropping his first decision in his last 11 April starts, Dempster was charged with six hits and five runs, while walking three and striking out four.
Marmol took over to walk both Reynolds and pinch-hitter Conor Jackson with the bases loaded. Justin Upton's bases-clearing double off Jeff Samardzija made it 9-0.
"The whole story, other than the fact we gave up 10 runs, was that we didn't score any," said Piniella, drawing laughs from the media crowded into his office.
The unintended laughs continued when Piniella tried to shake off any thoughts of panic by saying, "Look, it's only August ... April, I mean. Tell you what, after today it felt like August."
Way too premature to be thinking of the dog days, obviously.
"We just have to ride it out," said Soto, who credited Davis with taking advantage of the Cubs' overaggressive approach to his offspeed pitches. "We have to keep working hard, for a way to turn this around."