DENVER -- After a 10-4 blowout loss to the Colorado Rockies in the opener of their Tuesday doubleheader, Chicago Cubs catcher Miguel Montero said the team has to "wake up."

"The reality is, we can't take anything for granted, and right now, I feel like we do," Montero said after Game 1. "Honestly, we're just not playing at our highest level. We have to shake it up, wake up. This will be a good wake-up call for us. We either come to play the right way or we're going to have a short season."

The matinee loss was Chicago's fourth in a row and briefly dropped the Cubs to .500 for the first time since April 18. They would, however, go on to win the second game 8-1 to improve their record to 17-16.

The Cubs thought they caught a break when their game against the Rockies was rained out on Monday -- considering the team traveled all night from Chicago to Denver after losing in 18 innings to the New York Yankees. But the extra rest didn't help in Game 1.

During a six-run third inning for the Rockies, the Cubs made two defensive miscues behind starter Jake Arrieta, including a throwing error to third base by shortstop Javier Baez, followed by a bad read by center fielder Albert Almora Jr. that allowed three runs to score.

"We're all focused on hitting," Cubs manager Joe Maddon said. "I want us to play defense and pitch."

Arrieta's nine-hit, nine-run performance on Tuesday is emblematic of the Cubs' starting pitchers this season. Their collective performance has been way below the norm they set for themselves last season en route to winning 103 games and the World Series. Arrieta's ERA -- in a contract year -- ballooned to 5.35. As a rotation, the Cubs rank 11th in the National League.

"I didn't think it was good, at all," Arrieta said. "Just too many hittable pitches in the middle of the plate."

Montero offered his take.

"His stuff wasn't as crisp as it normally is and location wasn't there," Montero said. "He didn't get many swings and misses.

"When he threw a strike, he paid for it."

Arrieta has lost velocity on his fastball, but Maddon isn't concerned with any of his starters unless they're hurt. There has been no indication that's the case, but none has locked in after the long playoff run of a season ago. However, the short offseason should have nothing to do with the team's concentration. The Cubs just are not sharp right now.

"We have to stop making those [defensive] mistakes," Maddon said.

The Cubs know there's still plenty of time to turn it around, but no one could have predicted a near-.500 record even this early in the season, including their catcher.

"I think we played sloppy today," Montero said. "We've been playing sloppy. We all did. Simple as that. We have to change that."