Peacock, who dropped nearly 30 pounds last offseason, started last season in the Astros' bullpen and wound up making 24 starts, going 4-9 with a 4.72 ERA overall. He's a prime candidate to join the Astros' rotation when a need arises.
The Astros are going to use a six-man rotation this year at Fresno instead of the tandem starting pitching configuration they've used in past years. That being said, Peacock will tandem with another starter because he hasn't built up his innings yet.
Luhnow said the Astros will continue to use the modified tandem structure they used in the second half of last year at Double-A Corpus Christi and both Class A clubs -- Lancaster and Quad Cities. In that alignment, a starter would sometimes have a traditional bullpen work behind him in a game and at times be paired with another starter.
"We feel like a six-man rotation at Triple-A accomplishes our goals of keeping the workload reasonable and being able to evaluate guys we need to evaluate for the Minor Leagues and having them in a more familiar format when they get here," Luhnow said.
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.