So appearances notwithstanding, Cook (8-7) suffers on nights like Friday.
"For me, it comes with my temperament, my personality," Cook said of his consistent demeanor. "It's eating me up on the inside, knowing that it's one or two pitches.""
Cook, who gave up eight hits and walked three in six innings, yielded a Jason Kendall two-run single in the third inning and a two-out solo shot by Jacque Jones in the sixth. Cook was 3-0 with a 2.31 ERA in his previous five starts.
The Rockies also suffered another potentially costly injury.
First baseman Jeff Baker, whose throwing error on an attempted double play led to three unearned runs in the third, suffered what manager Clint Hurdle called "a mild concussion" when a delivery from winning pitcher Jason Marquis (9-7) hit him in the batting helmet and face in the eighth inning.
Baker was taken to a local hospital for observations.
Marquis gave up one unearned run on five hits and struck out five in 6 2/3 innings, but left immediately after hitting Baker. Marquis said he was trying to go low and away but "pulled off" of the pitch.
"You never want to see anything like that," said Marquis, who told reporters that he requested, through the Cubs, reports from the Rockies on Baker's condition.
Baker was in for Todd Helton, who missed his second straight start because of back spasms.
The Baker injury comes during a week when right-hander Jason Hirsh suffered a fractured fibula on a line drive, Helton was pushed off the field by his troublesome back and right-hander Rodrigo Lopez scheduled likely season-ending elbow surgery.
But the Rockies, who must win the next two with the Cubs to avoid seeing their streak of nine home series wins snapped, are resilient. It almost paid off Friday.
The Rockies loaded the bases with one out in the seventh. But Carlos Marmol, who replaced Marquis, fanned Willy Taveras on a slider after feeding him fastballs. Taveras, who went 1-for-4, had sat out the previous three games with a sore right quadriceps.
The Rox loaded them again off Marmol to open the eighth, but Bob Howry retired the next three batters, with one run scoring on Troy Tulowitzki's fielder's choice. Tulowitzki had an RBI double off Marquis in the fourth.
"We worked our way back into the game, but we got to hit with the bases loaded for four straight outs -- last out of the seventh, three outs of the eighth," Hurdle said. "We just couldn't come up with a big trump card to play out there, a single or anything.
"We'll work our way back in it, find a way to beat these guys."