The team's leadoff batter was batting a season-high .290 on June 29, but he's seen his average plummet 20 points since then. Gardner has just three hits in his last 34 at-bats entering Tuesday.
"I don't really see a lot of difference except he's not getting hits," manager Joe Girardi said. "It's important for him to get going, because he's a big part of our lineup."
Another big part of the team's lineup is struggling, too. Designated hitter Travis Hafner, the team's cleanup hitter, has been mired in a slump that has lasted more than two months.
After batting .318 with six home runs and 17 RBIs in April, Hafner has posted a .181 average with six home runs and 20 RBIs over May, June and July combined.
Hafner missed time earlier in the season with a shoulder injury that has plagued him throughout his career, but Girardi said the designated hitter hasn't said his shoulder is bothering him again.
"It's hard to put your finger on exactly why he's struggling, but he is," Girardi said. "But we need him to hit. That's the bottom line. We need this guy to hit. So we're doing everything we can to get him going."
Backup catcher Austin Romine's slump has lasted the entirety of his short Major League career. He's batting just .132 in 68 at-bats this season, with no home runs and two RBIs, entering Tuesday.
Girardi said he has been pleased with the rookie's defense behind the plate, though, and he still sees him as the team's backup catcher.
"I think his at-bats have been better. I do," Girardi said. "It's hard when you're used to playing every day, and for a young player to play once every four days, once every five days, it's an adjustment players have to make."
Josh Vitale is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.