SAN FRANCISCO -- After going 3-for-5 with an inside-the-park home run against the Giants on Aug. 20, rookie second baseman Jose Altuve has batted .172 (5-for-29) in his next seven games, which led manager Brad Mills to have him out of the starting lineup in Sunday's series finale.

"I don't want him to get in a situation where he gets too frustrated," Mills said. "I know he's getting hits now and then, which is good."

Indeed. Despite his weeklong funk, Altuve has yet to go more than one game without getting a hit. That's not surprising since Altuve tore it up in the Minor Leagues this year, hitting a combined .389 between Class A Lancaster and Double-A Corpus Christi before being called up by the Astros.

"Things might be happening a little fast right now," Mills said. "Is he seeing things he hasn't seen before? Well, he has, simply because he hasn't been in the Major Leagues that long. That's the easy answer. You get in a situation where this guy played so well for a couple of weeks or a month and you hate to see the frustration set in when he's not able to get a few hits when he wants to.

"He's got all the skills, all the talent in the world. I want him to relax and let it play out."

Mills believes in Michaels vs. lefties

SAN FRANCISCO -- Astros manager Brad Mills continues to use a platoon in right field, with Jason Michaels or Jason Bourgeois starting against left-handed pitchers and Brian Bogusevic starting against right-handers, like he did Sunday when Matt Cain was on the mound for the Giants.

Bogusevic has only five at-bats against lefties this year, going 1-for-5, and Mills admitted he'd like to get him more at-bats against southpaws in the future. But for now, the skipper is content to let Michaels and Bourgeois get most of the time against lefties.

Michaels is hitting .196 this season, including .208 against lefties, while Bourgeois is hitting .359 against left-handers.

"J-Mike's with us and in the past he's been a real good hitter against left-handers, so we'd like to give him a chance," Mills said.

Mills says he understands the frustration of the fans, who would like to see Bogusevic get regular starts against left-handers.

"I totally understand that, but at the same time let's give him a little bit more time," he said. "Let things play out a little bit more, and we'll see where he's at."

Carpenter making adjustments in warmups

SAN FRANCISCO -- Astros pitching coach Doug Brocail has taken the unusual step of having rookie right-hander David Carpenter throw 10 fastballs in the bullpen after he warms up every day in an effort to refine his mechanics, and Brocail might begin doing it with other pitchers, too.

With Carpenter, Brocail is working extensively with him to try to keep his front side from flying open during his delivery. The work has already paid off, and Brocail said Carpenter has developed a true slider instead of a ball that breaks down and looks like a cutter.

"It gives us the ability to work together instead of me having to explain what went wrong as soon as he comes out of games," Brocail said. "This way, we can continue to build on it. I can see how excited he is when I know he's doing the right things."

Carpenter, a former catcher in the Cardinals organization, was acquired by the Astros in a trade last year in exchange for Pedro Feliz. He dominated at Double-A and Triple-A this season and has gone 0-2 with a 3.00 ERA in 22 games with the Astros, entering Sunday.

"He searches for a lot of knowledge and he'll ask 1,000 questions with you," Brocail said. "He's just trying to get better, and now instead of me having to do it in the dugout, we can work on it as soon as they're done warming up. At the end of it, we just throw 10 off the mound. He's been doing it since [Monday] and it's really made a big difference."

F. Rodriguez thriving as reliever

SAN FRANCISCO -- Fernando Rodriguez is nine years into his professional career, but he's still relatively new at the relief pitcher thing. He made the transition to the bullpen from the rotation late in the 2008 season while with Triple-A Salt Lake of the Angels organization.

Rodriguez initially took the move as a demotion, but he's flourished in a relief role and has spent most of this season on the Major League roster. He had appeared in 36 games prior to Sunday and was 2-3 with a 3.35 ERA with 45 strikeouts in 40 1/3 innings.

"I always wanted to be a starter, and once they threw me in the bullpen I was thinking my career was over," said Rodriguez, a Texas native who was drafted by the Angels in 2003 and signed by the Astros as a Minor League free agent last winter.

Rodriguez, who had appeared in only one Major League game prior to this season, hopes he has found a home in Houston, but he's not going to take anything for granted.

"Every day is always a battle because nothing's for sure," he said. "You have to go out there and do your job, and even on days you don't get it done, you've just got to realize what you did wrong. You have to not make the same mistakes the next time you're in the same situation. I'm trying to throw it all out there for them and putting it on the table to show them what I can do."

Worth noting

• Catcher Jason Castro, who is going to miss the entire season after having right knee surgery in Spring Training, will join the club Monday to continue his workouts in Houston. Castro has been working out with the Astros' Gulf Coast League team in Kissimmee, Fla., and he'll catch in the bullpen and take batting practice with the Astros until instructional league starts.