He said going down to San Antonio allowed him to focus on some smaller things that might matter more as a starter, like controlling the running game, in lower-stress situations.
"When you have to deal with six, seven innings with guys running, you know you really have to make a point to control that and get your times down and get your catcher a chance, or it's going to be long game," Cashner said.
The right-hander also worked on his fastball command, as well as his hitting. He took some batting practice before Wednesday's game at Minute Maid Park, mostly focusing on bunting.
"I'm still struggling there," Cashner said. "It'll get there, though."
Manager Bud Black said the purpose of sending the 25-year-old to the Minors for three starts was to help him build arm strength and adjust to the off-day work that starters do: running, conditioning and side sessions.
"We all feel as though he's in the right spot physically and mentally to start a Major League game, and feel confident throwing 100 pitches or more," Black said.
After coming over to San Diego from the Cubs in the Anthony Rizzo trade in January, Cashner pitched 28 1/3 innings in 28 appearances out of the bullpen, posting a 3-3 record and a 3.81 ERA.
Cashner said he was surprised to be moved to a starting role so soon after being told in Spring Training that he would probably work solely as a reliever in 2012. Black said if things go well for Cashner, he could continue to make starts for the rest of the season.
Born and raised just 40 miles from Houston, Cashner said he will have lots of family and friends at Minute Maid for Thursday's game. He went to Texas Christian University after graduating from Conroe High School.
"It's exciting," Cashner said. "I've got a lot of friends that haven't ever got to see me pitch."