Hendriks, 23, is winless in 12 career starts, with a career 6.71 ERA. He has a 7.04 ERA in eight outings this season.
He appeared in line for his first win on Monday, as he took a 6-1 lead into the fifth inning, but he allowed four straight runners to reach base and was pulled from the game in favor of reliever Anthony Swarzak.
"He wasn't commanding his pitches, he wasn't aggressive in the zone, he wasn't attacking hitters -- and, you know, he gets staked to a 6-1 lead and he looked like he was pitching scared, like he was trying to get through an inning," assistant general manager Rob Antony said. "And that's not him. When he's effective, he's attacking the hitters, keeping the ball down in the zone and using all four pitches. He was choking off his breaking ball. I think he just mentally needs to regroup."
De Vries, meanwhile, pitched well against the Royals on Saturday, allowing one run on five hits over six innings. But he was called up that day as the 26th man for a doubleheader, and was optioned to Rochester after his start.
De Vries will take Hendriks' spot in the rotation, which means he's slated to start Saturday against the Rangers in Texas.
He's also expected to be available in the bullpen Tuesday in case of emergency, as the bullpen has been depleted since Saturday's doubleheader.
"It would be a bullpen session for him, so he'll be available out in the bullpen," Twins manager Ron Gardenhire said. "Hopefully we won't be able to use him, but definitely available."