CINCINNATI -- The Astros placed closer Brandon Lyon on the 15-day disabled list Thursday after he was diagnosed with biceps tendinitis and a partial tear of the rotator cuff. The team said Lyon will be treated non-surgically and recalled right-hander Jose Valdez from Triple-A Oklahoma City.

Lyon, who blew his fourth save in eight tries Wednesday, returned to Houston on Thursday afternoon to undergo an MRI and be examined by team medical director Dr. David Lintner. Lyon has been experiencing weakness in his right shoulder.

"We've had some questions about whether the arm strength in there has been exactly what it needs to be," said Astros manager Brad Mills, who has appointed right-hander Mark Melancon as the closer in Lyon's absence.

Lyon's velocity has been down, and he allowed all five batters he faced in the ninth inning Wednesday to reach, letting the Reds to rally for a 3-2 win in the ninth. Lyon didn't speak to reporters after the game, but the team announced early Thursday he was going to Houston.

"He's been on the [daily medical] treatment sheet with a little bit of a biceps tendinitis type of thing, but the more they talked yesterday Brandon acknowledged he had some weakness in his shoulder so we just felt it behooved us to get him back into Houston and see Dr. Lintner and try to determine what the best course of action will be," Astros general manager Ed Wade said.

Lyon had a small cyst drained in his shoulder in January, 2010, but it's not known if his current shoulder problem is related.

"We don't need him to try to be heroic at this point in time and fight through something that won't resolve without rest," Wade said. "If rest is the proper course of action, it makes sense for us to give him that opportunity. We saw it last year what he did for us the second half of the season. He had 19 saves [after Aug. 1], one of the best in baseball in the second half. We need that type of effectiveness, but at the same time we need to give him the opportunity to get to where he needs to be."

Lee works out, eyeing weekend return

CINCINNATI -- Astros left fielder Carlos Lee took batting practice, played catch and fielded fly balls in the outfield on Thursday prior to the Astros' 10-4 loss and was pleasantly surprised with the results. Lee has been out since suffering a bruised rib cage in a collision on Sunday.

"A lot better than expected," he said. "The more I got warmed up, the better I felt. Swinging the bat is not a problem. I was chasing balls in the outfield and I ran pretty good. It's just a matter of getting comfortable with the pain. It's not going to go away overnight or in the next day or two, but I've got to get used to it."

Lee spent Sunday night in a Houston hospital after being kneed in the ribs by shortstop Angel Sanchez when both where sliding in the outfield in an attempt to catch a pop up. Lee was carted off the field in pain but suffered no broken bones or damage to any internal organs.

He's hopeful he can return to the field this weekend in Pittsburgh, as long as he can manage the discomfort.

"When you run, when you throw and you swing, you're going to feel it," he said. "It's in the middle part of your body and everything goes though there. Actually, I feel pretty good. I was chasing some balls in the outfield and threw some balls and swung the bat. I thought it was going to be a lot worse."

Hall ejected for arguing balls and strikes

CINCINNATI -- Astros second baseman Bill Hall was critical of the umpiring following his team's 10-4 loss to the Reds on Thursday. Hall was ejected in the seventh inning by plate umpire Tom Hallion for disagreeing with a pair of balls-strikes calls.

Hall took a pair of called strikes in his at-bat in the seventh, then took his time getting back in the box, which he says irked the umpire. After striking out swinging, Hall said he cussed at himself loudly in frustration and was thrown out.

An inning earlier, Chris Johnson spiked his helmet to the ground when he struck out, then exchanged some words with Hallion.

"It's amazing how umpires can get away with so much stuff and nothing happens to them," Hall said. "It's all about them trying to get something on ESPN punching someone out or getting their spot on ESPN. I have no idea. It's getting ridiculous. It's gotten worse over the last few years, and hopefully, somehow, someway it can be calmed down a little bit because it's a little out of hand."

Hall maintained the first two pitches weren't strikes.

"I didn't really say anything to him, and once I got out of the box, he was yelling at me, cussing me out, telling me to get the in the box," he said. "You don't rush anybody else to get in the box. Just because I disagree with the pitch, I still didn't say anything to you about it, so there's no reason to rush me into the box."

Hall said he was upset following the at-bat but was on his way to the dugout. He didn't make it without being ejected.

"It was just ridiculous," he said. "The whole situation was ridiculous. You are mad at me because you're missing pitches, but at the same time, I'm not disrespecting you, but he felt the need to disrespect me?"

Hall said umpires aren't getting punished enough for mistakes.

"They feel like they can go out there and 30,000 people are out there to see them when they're not," he said. "They're out there to watch us. As long as we're not disrespecting you and getting in your face and showing you up in ways where you need to throw people out of the game, then they just need to calm down.

"Because right now, it's a joke the stuff they can say on the field and stuff they do on the field, and when we get mad, we're the one that gets tossed and gets fined and suspended for games. And most of the time they don't get anything."

Michaels will begin rehab stint Saturday

CINCINNATI -- Astros outfielder Jason Michaels, who is on the 15-day disabled list with a left shoulder subluxation (partial dislocation), will begin a Minor League rehab assignment on Saturday with Triple-A Oklahoma City.

Michaels, who has two hits in 18 at-bats this year, injured his shoulder while diving for a ball in the outfield on April 24 at Milwaukee. He took batting practice on the field Thursday afternoon and said he was ready to go.

"The more at-bats I get, the better," he said. "But it felt good today."

Michaels, the club's fourth outfielder, batted .253 with 14 doubles, eight home runs and 26 RBIs in 106 games last year and had a terrific spring. He's struggled at the plate so far this season, but has started just three games in left field.

Worth noting

• Telvin Nash, the slugging Astros prospect at Class A Lexington, is expected to miss about six weeks after breaking the hamate bone in his left hand. Nash, who hit three homers in a game earlier this year and is hitting .394 with five homers and 11 RBIs, will have surgery on Wednesday.

• Triple-A Oklahoma City catcher Carlos Corporan broke the middle finger on his right hand and will be out for about a month. The club has promoted catcher Brian Esposito to Oklahoma City and catcher Jonathan Fixler to Double-A Corpus Christi.