Nieuwenhuis, who has one hit in his last 14 at-bats, was not in Wednesday's starting lineup. Manager Terry Collins said he wants the 2008 Draft pick to work with hitting coach Dave Hudgens to fix his swing, which he said has been dragging into two parts.
"He's really struggling. I try to make sure that we don't get some of these young players in a deep pit where they all of a sudden start questioning whether they belong here or not."
Nieuwenhuis' struggles have only occurred for the last couple weeks. He began June with four multi-hit performances in his first 14 games and has blasted five of his seven home runs this month.
More than just batting average or power, Collins wants Nieuwenhuis to get on base out of the leadoff spot. Collins said he thinks the main problem with the young outfielder is he's not seeing the ball well and he's pulling his head out.
"We've got to start getting him on base," Collins said. "If you're going to lead off, you've got to get on. That's part of the job. We know he can do some damage. If he gets a pitch to hit he can hit a homer."