PHOENIX -- The Dodgers placed outfielder Trayce Thompson on the 15-day disabled list with an unspecified lower back injury on Saturday, retroactive to July 10, and recalled utility man Zach Walters from Triple-A Oklahoma City.
Thompson has been dealing with lower back issues since June but aggravated the area on a swing last Sunday, manager Dave Roberts said. The club has said he has irritation in his lower back, but has not provided an injury. This is the 20th time the club has used the disabled list this season.
"He just couldn't be the player that he was," Roberts said. "When you're talking about the back and what we have left in the season, we didn't want to put him in harm's way. We have the opportunity to have days backdated, not lose too many days on the calendar, and it just made sense to get him back to 100 percent." 
Thompson went 5-for-35 on the recent homestand and saw his average sink to .225, so he also figures to work on his swing while he's out. 
Walters, 26, was purchased by the Dodgers from Cleveland in April. Originally drafted by Arizona in 2011, he has played briefly in the Major Leagues for Washington and Cleveland, most recently last year.
"Zach can play anywhere, a switch-hitter, and with a four-man bench, to have the ability to have a player that can play both corner-outfield spots and anywhere in the infield, it gives me flexibility," Roberts said.
While at Triple-A Oklahoma City this year, Walters hit .298 with an .836 OPS, 10 homers and 47 RBIs in 77 games. He credited OKC hitting coach Shawn Wooten with leading to his offensive improvement.
"He just made fun of me that I was raw, had no idea to repeat a swing, and he worked with me and I have an idea what I'm doing now," Walters said. "I can take constructive criticism, something I need. Coming here has been a blessing, especially with him."