In 15 games, the Cubs No. 3 prospect was batting .276 with two home runs, three doubles and seven RBIs. The Cuban outfielder already has served a five-game suspension for charging the opponent's dugout, carrying a bat. On Saturday, he was 0-for-4.
"As a coaching staff, we're required to stay on top of it," Keller said. "And we're doing it because work habits create the player, period. When you work, you get better."
Theo Epstein, Cubs president of baseball operations, has emphasized that players at all levels in the organization, play the game the right way.
"Our managers are encouraged to bench players who are giving less than 100 percent effort -- whether that's failure to hustle down the first-base line or failure to properly prepare for a game," Epstein said. "It's our responsibility to make sure every player in the organization demonstrates preparation, hustle and effort every day with no exceptions.
"Playing time is still the best way to get a player's attention. These actions are intended to remain in house. Many players have been benched for this reason already this year and have responded immediately with proper effort. Soler is not alone, and, in fact, he has shown a real interest in learning to play the game the right way."
Cubs manager Dale Sveum said the best thing is to make sure all players know lackadaisical play is not acceptable.
"The one thing we want to stay in touch with here is accountability," Sveum said. "Not everybody is going to run every single ball out 100 percent. That's just part of the game, but you get a grip on it and hold people accountable and move on."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.