"We came out flat," Keuchel said, according to Daryl Van Schouwen of the Chicago Sun-Times. "We have some guys taking professional at-bats, being professional on the mound, and doing what it takes to win, and we've got some guys going through the motions. So, we need to clean a lot of things up.
"It seemed like we were taking the night off ... very subpar play from everybody."
The White Sox mustered a single run against the Tigers despite recording eight hits on the night. They went 0-for-3 with runners in scoring position and failed to capitalize on a solid outing from the veteran southpaw. Keuchel allowed three runs on six hits over six innings of work.
Keuchel made his comments to the entire locker room after the game.
The message was apparently received well.
"Somebody had to say it," shortstop Tim Anderson said, according to Van Schouwen.
Chicago entered the season as a possible postseason challenger with the additions of veterans like Keuchel, catcher Yasmani Grandal, and slugger Edwin Encarnacion to an impressive young core featuring Eloy Jimenez, Yoan Moncada, and rookie Luis Robert.
However, things haven't gone smoothly as of late, as the 8-9 White Sox have now lost five of their last six games. Meanwhile, the Tigers - who were largely expected to be one of baseball's worst teams - improved to 9-5.
Though Keuchel was critical of Monday night's effort, he expressed confidence that the team will rebound.
"There's going to be a lot of learning curves for this team, just because of the process that this team has been under the last two, three years. This is one of them," he said. "We faced a challenge tonight, and hopefully we can come out tomorrow and strap it up and play some White Sox baseball."
Keuchel, 32, won the AL Cy Young in 2015 and was a key piece for the 2017 World Series champion Houston Astros. He signed a three-year, $55.5-million contract with the White Sox this past offseason.