DENVER — Tyler Matzek started strong, faded late. It was simply a microcosm of the Colorado Rockies' season.
Matzek cruised through five innings but couldn't sustain it, faltering in the sixth and seventh innings as the San Diego Padres beat the Rockies 6-1 on Monday night.
Slumping Colorado lost for the 18th time in the last 21 games and fell into last place in the NL West.
It is a stark contrast to how the Rockies started the season. They won their first six series at home, but are 5-16 at Coors Field since June 3.
The last time they won a series at home was May 16-18 against San Diego.
"We can't afford to lose series, we've got to start winning series," manager Walt Weiss said. "We're getting some guys back, but bottom line is we have to start winning some series."
Matzek gave his team a chance early to win the first of this three-game series. He worked out of trouble in the first three innings before allowing a sacrifice fly to Brooks Conrad in the fourth.
"My first few (innings) my stuff felt good," he said. "I was just trying to attack the zone."
For a while he kept pace with Kennedy, who pitched seven sharp innings. Chase Headley added four hits for San Diego, including a two-run triple in the seventh inning to break open a close game.
Kennedy seemed to gain strength the deeper he got into the game, striking out five of the last six batters before wind, rain and lightning forced the delay heading into the eighth inning. Kevin Quackenbush stepped in for Kennedy when play resumed.
Kennedy (7-9) finished with nine strikeouts, boosting his team-leading total this season to 125. He allowed four hits in seven innings, including Stubbs' leadoff home run in the fourth.
"He's always been effective and he's been effective his last few starts," outfielder Corey Dickerson said. "His fastball sneaks up on you and he elevates it. He's got a good off-speed curveball, and I feel he makes you swing at some pitches he wants you to swing at."
San Diego's starting pitchers have allowed only six runs over the last seven games, helping the Padres go 5-2 in that stretch.
The Padres improved to 28-4 this season when scoring four or more runs, the second-best mark in baseball behind Washington, which is 39-3 when scoring at least four times.
Kennedy got all the support he needed after the fifth.
With the score tied 1-1 in the sixth, Tommy Medica hit a one-out double and Rene Rivera followed with a double to left. One out later, Cameron Maybin sent a drive to the warning track in left center that seemed to get caught in swirling winds and dropped just beyond the reach of Dickerson's glove as the Padres took a 3-1 lead.
"I felt like I got there pretty good and then I saw Stubbs pretty close," Dickerson said. "Nobody called it so I called it but I felt he was still running, too. It was a difficult play."
San Diego added three runs in the seventh. Kennedy drew a leadoff walk and Chris Denorfia singled to chase Matzek (1-3). Headley greeted Matt Belisle with a triple off the right-field wall, scoring Kennedy and Denorfia. Carlos Quentin's sacrifice fly put the Padres in front by five runs.
Matzek was charged with five runs and eight hits in six-plus innings. He walked four and struck out four.
"I started falling behind guys. I was picking corners and trying to be fine," Matzek said. "First-pitch strikes are the most important thing. You get hitters in hitters' counts and they're going to hit the ball."
NOTES: Padres RHP Tyson Ross is slated to start Tuesday's Game 2 against LHP Franklin Morales and the Rockies. ... Stubbs is batting .333 (6 for 18) with two home runs midway through the Rockies' 10-game homestand. ... Rockies batters struck out 13 times in all.