Koehler returns to Miami after being optioned to New Orleans on July 4, when the club reinstated starter Henderson Alvarez from the 60-day disabled list.
During his stint in the Minors, Koehler worked on improving his consistency.
"We've been working pretty much every day to try to work on the consistency and the delivery and the quality of pitches," Koehler said. "With the bullpen [sessions] down there, the game and everything was just trying to repeat the delivery and sharpen up a couple of the breaking balls and basically making sure that everything was as consistent as possible."
In 10 starts and 16 total appearances with the Marlins, Koehler has gone 1-5 with a 4.70 ERA and a 1.23 WHIP. He notched four quality starts, three of which came during his first four turns in the starting rotation.
Koehler began his first stint in the Majors this year when Miami recalled him from New Orleans after designating John Maine for assignment on April 19.
The 27-year-old made his first appearance on April 20. He walked two and struck out one in two scoreless innings of relief in a 3-2 loss to the Reds in Cincinnati.
Koehler made one start for the Zephyrs after he was optioned, giving up five runs on nine hits in six innings on Monday in a losing effort. He has gone 0-2 with a 2.74 ERA and a .200 opponents batting average in four starts with New Orleans.
Joe Morgan is an associate reporter for MLB.com This story was not subject to the approval of Major League Baseball or its clubs.