The latest in a rash of injuries to the Rangers' starting rotation -- this time to Eric Hurley and Vicente Padilla -- have opened up a door for Harrison to make his debut. Rookies David Murphy, Max Ramirez and Chris Davis started Monday against the Angels. Rookie third baseman German Duran is also on the 25-man roster.
"We wouldn't do this if we didn't think Matt was ready," general manager Jon Daniels said of Harrison. "He's a strike thrower. He's got a good pitch mix. He's got a mound presence. He's most deserving of this opportunity at this point."
Harrison has split time between Double-A Frisco and Triple-A Oklahoma this season, and is a combined 6-3 with a 3.43 ERA in 15 starts in 84 innings. He allowed one earned run in six innings in his last outing on Thursday. He had five strikeouts and two walks.
The Rangers were going to have to wait until after Monday's game to make the corresponding roster move in order to add Harrison.
Even with Harrison making his first start, there is still much unsettled with the Rangers' rotation.
Hurley might start Wednesday's game, but is not confirmed to do so. The righty's left hamstring felt better Monday, but during some fielding drills, he wasn't 100 percent.
The Rangers don't want to take any risks, but Daniels said they also want to avoid putting Hurley on the disabled list, even with four days off for the All-Star break.
"We want to make sure he's ready when he goes back out there," Daniels said.
The Rangers also are uncertain if 10-game winner Padilla will pitch again before the All-Star break. Padilla was supposed to see team doctor Keith Meister before Monday's game against the Angels.
As it stands now, the Rangers are in the midst of starting four young pitchers against the Angels -- Luis Mendoza on Monday, Hurley -- possibly -- on Wednesday and Scott Feldman on Thursday.
"We're going to give them a chance to dig deep and see what they're all about," Washington said before Monday's game. "I do believe, even though they're young, if you throw the ball over the plate, and the good ball we've been playing lately, they have a chance to win."