HOUSTON -- Astros center fielder Jordan Schafer was placed on the 15-day disabled list prior to Tuesday's game with a left shoulder separation. The injury is to the acromioclavicular (AC) joint, which is a separation of the collar bone from the shoulder blade.

The Astros closed the home clubhouse to the media for 45 minutes prior to Tuesday's game against Washington before announcing the Schafer move. Schafer began experiencing discomfort in his shoulder during the Astros series over the weekend in Atlanta, manager Brad Mills said.

"He woke up Sunday morning and his left shoulder was really bothering him," he said. "He showed up [Monday] and it felt fine, and then it progressively got worse during the game."

Schafer, who had a similar injury in 2009, was examined by team doctors Monday night before it was determined he would be placed on the DL. He's hitting .216 with four homers, 23 RBIs and 26 stolen bases, which ranks tied for sixth in the National League this year.

"Obviously you never want to go on the DL, but it's just a fact you can't have somebody down and not being able to play for an extended period of time," Schafer said. "For the best of the team it's the best thing we can do right now."

This has been a frustrating season for Schafer, who got out of the gate quickly but has struggled mightily at the plate for much of the season while battling a series of nagging injuries. He's hitting .159 (21-for-132) since June 3 with 46 strikeouts.

"It's been frustrating," he said. "The whole season's been like this after the first two months -- it's gone downhill for me and for all of us in this organization as a team. We haven't been very successful. It's sad but it's something that happens and I just need to get healthy."

Barnes overjoyed by callup to big leagues

HOUSTON -- Brandon Barnes was called into the office of Triple-A Oklahoma City manager Tony DeFrancesco following Monday's game in Salt Lake City to supposedly talk about the game. DeFrancesco's real reason for summoning the outfielder had a much bigger meaning.

"We were just talking some stuff about the game and he just said, 'You're going to the show,'" Barnes said. "I kind of sat there like, 'Really?' Tears came, obviously. It was just excitement. I got to call my wife and she started crying. It was fun."

Barnes, who will wear jersey No. 39, was in the lineup Tuesday in center field, batting seventh, in his Major League debut. To make room for Barnes on the 40-man roster, the Astros designated Oklahoma City right-hander Juan Abreu for assignment.

"I've been in this game for eight years with the same organization," Barnes said. "It's been a grind for me. Last night was definitely something that was unexpected. It was probably the second best night of my life, other than my daughter being born. It came out of nowhere to me."

The 26-year-old Barnes, Houston's sixth-round selection in the 2005 First-Year Player Draft, was batting .323 in 62 games for Oklahoma City. He hit .317 in 44 contests at Double-A Corpus Christi earlier this season.

"There were a couple points in my career when I just wanted to shut it down," Barnes said. "I felt like this might not be the game for me. It was tough. This game's a grind. I just kept going. My wife pushed me, my family pushed me and told me I can do it. I kind of just got back on the horse and kept going on the grind. Hard work pays off and it finally has for me."

Barnes' wife, Shawn, and 1-year-old daughter, Kenadie, were expected to be at the game Tuesday, along with Barnes' parents, his best friend and two pastors from his church.