VandenHurk is lined up to start on Saturday against the Dodgers in Los Angeles. Because of off-days on Thursday and on July 27, the Marlins can go with a four-man rotation until either July 31 or Aug. 1, depending on how they want to shuffle their starters.
"My last two outings, I didn't get out of the third inning," said Miller, who is 3-5 with a 4.81 ERA. "The last couple of games, I haven't had command, at all. I've got to find out what it is to get it back, and throw strikes."
Miller is coming off a loss on Sunday against the Phillies in Miami. The 6-foot-8 lefty gave up four runs in 2 2/3 innings. It was his second straight start of 2 2/3 innings. He also went that distance on July 9 at Arizona, in a no-decision.
"We need to get him straightened out," Marlins manager Fredi Gonzalez said. "We'll let him go down there, get a couple of starts, and bring him back up.
"We've been kicking this around for a couple of days now. We could have easily made a hasty decision last night, and we didn't. We had meetings. We tried to do what's best for the kid and for us. We think this is the best."
The Marlins haven't said who will fill Miller's roster spot. The team carried 13 pitchers on Monday and may opt to go back to using another position player.
New Orleans played at home on Monday. Some possibilities are outfielders Cameron Maybin or Alejandro De Aza. Infielder Gaby Sanchez also is a candidate.
Maintaining a consistent delivery has been an issue for Miller throughout his big league career. He opened the season pitching out of the bullpen before becoming the fifth starter.
The Marlins obtained Miller from the Tigers as part of the Miguel Cabrera/Dontrelle Willis trade in December 2007. For his career, he is 14-21 with a 5.50 ERA, and he's 9-15 since joining the Marlins.
Miller twice this season had matched his career high with seven innings. His last win was on July 4, when he gave up three runs in 6 2/3 innings against the Pirates.
"It's not a question of can I do it or whatever," Miller said. "It's can I do it consistently? I've proven that I can pitch for stretches, it's how can I eliminate pitching in the bad ones.
"I'll go down there and work on some stuff, figure some stuff out, and come back as soon as possible."