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05/04/10 2:27 AM ET

Astros aim to halt slide against D-backs

It doesn't take an Einstein to figure that the math hasn't been working in the Astros' favor. During this seven-game losing streak, which they'll try to end Tuesday night against the D-backs, the Astros have scored a grand total of 13 runs.

That's less than two runs per game for those scoring at home. Even if Houston had the greatest pitching staff ever assembled, those are tough numbers to overcome.

"It's not just about the offense scoring runs," Houston manager Brad Mills said. "A lot of times when the team scores runs, it overshadows some of the other things, whether the team happens to run the bases wrong or errors they make or the pitching has a tough time. If you score a lot of runs, that covers up a lot of those mistakes. Right now, we're not scoring the runs, and so the mistakes don't quite get covered up.

"We've run the bases very well most of the time. We've pitched extremely well most of the time, so when we start scoring runs and hitting like we're capable, everything is going to be in the right direction."

That happened, at least to a greater extent, during an 8-2 stretch in the latter half of April. That helped largely erase the 0-8 start the team had this season, and it will need the bats to come back starting on Tuesday if the Astros want to avoid matching that opening losing streak.

They had never faced rookie Cesar Valdez, who was making his Major League debut, on Monday, and he went five innings for a win to help Arizona climb within two games of .500. Familiarity won't breed anything on Tuesday since young right-hander Ian Kennedy will be facing the Astros for the first time in his career. Kennedy has gone eight innings in each of his past two starts, and as luck would have it, lost the game he pitched better in (8 IP, 2 ER) and won the one where he wasn't quite as sharp (8 IP, 5 R, 4 ER). He has, at the very least, kept his team in the game in all but one of his five starts this season.

The Astros do have the right guy on the mound to try to stop the slide. Roy Oswalt has a tidy 2.73 ERA for the year, though just a 2-3 record to show for it. And he likes seeing the D-backs in the opposing dugout. Oswalt will be aiming for his 10th win -- vs. just one loss -- against Arizona and has a 1.96 ERA over 11 career starts. He hasn't been beaten by the D-backs since May 27, 2007, and over his past three starts against Tuesday's opponent, he's yielded just one run over 22 innings. That being said, all that history will be for naught if the Astros' struggling lineup can't figure out a way to get to Kennedy.

"He's good, bottom line," D-backs manager A.J. Hinch said of Oswalt. "We need to make him work. When you go against an ace, a top guy, maintaining your game plan is important. He does throw a lot of strikes. He does throw four pitches. He competes his tail off and we need to show up to beat him."

D-backs: Did anyone tell LaRoche what month it was?
Kelly Johnson deservedly was named the National League Player of the Month for April on Monday, but no less astounding than what Arizona's second baseman did in the season's opening month is what the guy who shares the right side of the infield accomplished.

Adam LaRoche's April may have been good, but nothing spectacular when taken without any historical context. A first baseman hitting .296/.390/.563 with four homers and 17 RBIs is fine. When his career April stats are considered, however, it looks a whole lot better. LaRoche has a well-earned reputation as a slow starter and this April brought his career opening-month line to .211/.304/.396. If things continue to follow suit -- historically, his OPS goes up by nearly 130 points in the second half compared with the first -- he could be in line for a career year in his first season with Arizona.

Astros: Roster shuffle changes pitching staff
Following Monday night's game, the Astros made a pair of roster moves that impacted the pitching staff.

Lefty reliever Tim Byrdak was put on the 15-day disabled list with a right hamstring strain. At the same time, Sammy Gervacio was sent down to Triple-A Round Rock. Right-hander Wilton Lopez was recalled and lefty Gustavo Chacin, who had to be added to the 40-man roster, officially had his contract purchased.

This is Lopez's second stint with the big club -- he made four relief outings earlier this season -- and got the win for Round Rock on Monday night against Nashville. Chacin is back in the big leagues for the first time since pitching for the Toronto Blue Jays in 2007. He's got a career 25-15 record and a 4.18 ERA in 58 career starts in the Majors.

Worth noting
The D-backs now lead the all-time series with the Astros, 49-39. ... Arizona catcher Chris Snyder has now played 215 consecutive games without an error. It's the third-longest streak in Major League history, behind Mike Redmond, who's at 248 and counting, and Mike Matheny (252). ... The Astros haven't hit a home run in the past four games. Their last roundtripper came in the seventh inning on Thursday against the Reds. Their three doubles on Monday gave them five extra-base hits total during this stretch.

This story was not subject to the approval of Major League Baseball or its clubs.