KISSIMMEE, Fla. -- First baseman Jon Singleton was among four players optioned to the minor leagues by the Houston Astros, who said rookie Asher Wojciechowski had made their starting rotation and will start April 9 against Cleveland.
Outfielder Alex Presley was designated for assignment.
The 23-year-old Singleton batted .168 in 95 games for the Astros last season and struck out 18 times in 50 at-bats during spring training.
"Jon has some of the best bat speed on this team, some of the best power on this team," manager A.J. Hinch said Wednesday, "and we've got to find a way to bring out a consistent swing that works for him."
Singleton's demotion leaves Chris Carter as the first baseman. Carter, whose 37 home runs were tied for second in the major leagues, played 14 games at first base last season and was primarily the club's designated hitter.
Hinch declined to announce a regular DH. Evan Gattis, acquired from Atlanta during the offseason, will see time at DH and also left field, a new position for him.
Houston put three pitchers on the 15-day disabled list: Brett Oberholtzer (blister on left index finger), Brad Peacock (hip surgery) and Josh Fields (right groin strain). Oberholtzer's move was retroactive to March 31, Peacock to March 30 and Fields to March 27.