The team optioned Gomez to Triple-A Columbus and recalled left-hander Scott Barnes from the Clippers before the opener of a three-game series against the New York Yankees. Barnes will work out of the bullpen.
The Indians expect to recall McAllister from Columbus to start Thursday night in Baltimore, and manager Manny Acta confirmed that the 6-foot-6 right-hander will get several chances to prove he belongs in the rotation.
"When Zach came up earlier, he threw the ball well for us," Acta said. "So it's not a one-and-done tryout type of thing."
Gomez had been with the Indians all season. The right-hander is 4-7 with a 5.18 ERA in 14 games, including 13 starts.
He got off to a great start Saturday in Houston, but was undone by his struggles in the fifth inning. He allowed five runs and six hits in 5 2/3 innings of an 8-1 loss to the Astros.
"It's about consistency throughout the game, throughout outings every five days, staying aggressive with his fastball and pitching ahead in the count," Acta said. "Getting back to being more consistent with his delivery from the stretch, because he's run into a lot of trouble with that, not being able to stay back and leaving pitches up in the zone. So, they got the instructions over there in Triple-A to get him back to where he was."
The 24-year-old McAllister went 1-1 with a 3.96 ERA in four starts for Cleveland earlier this season. He struck out 22 and walked six in 25 innings.
A third-round draft pick by the Yankees in 2006, he was traded to the Indians in 2010 as the player to be named later in a deal for reserve outfielder Austin Kearns.
McAllister is 5-2 with a 2.98 ERA in 11 starts at Columbus.
"He has continued to throw the ball well for us down there," Acta said.
The 24-year-old Barnes was with the Indians from May 30 to June 14. He compiled a 10.38 ERA in 4 1/3 innings, though three of his four relief appearances were spotless.
Cleveland began the day 37-34 and a half-game behind the first-place Chicago White Sox in the AL Central despite a 4.54 ERA, which ranked 28th out of 30 major league teams.
In other news, Acta said injured designated hitter Travis Hafner was scheduled to run Monday and slide Tuesday. If all goes well, he could begin a minor league rehab assignment in a couple of days.
The oft-injured Hafner has been on the 15-day DL since May 24 because of right knee surgery.