HOUSTON -- Perhaps there is a reason Jack Wilson appears so indispensable to the Pirates.

Consider the pivotal play in their 6-4 loss to the Houston Astros yesterday at Minute Maid Park, a game Wilson had to miss because of a sore right shoulder ...

The score was 3-3 in the seventh, and new reliever Steven Jackson, despite barely allowing a ball to be struck with authority, had runners at first and second with two outs. Miguel Tejada hit a roller up the middle, and shortstop Ramon Vazquez had to dive to keep it in the infield, then flipped right from his glove to Freddy Sanchez at second in hopes of a forceout.

Two problems with that: One, the speedy Michael Bourn was in there easily. Two, Matt Kata, who had been on second, never stopped sprinting and went all the way home with the tiebreaking run. Sanchez never made a throw.

It is a play Wilson might have made without the dive, given his far superior range.

"It's a tough play," Pirates manager John Russell said. "It's Bourn going into second and, if Ramon tries to jump up and throw the ball home himself, that would be tough, too, because of the dive."

Vazquez's thinking was to flip to Sanchez because, even if Bourn was safe, Sanchez had a better angle at home.

"That's what I wanted," Vazquez said. "It took me a long time to get to it because we were playing Tejada in the hole. I knew it would be close at second, but I also knew it would be hard to get up and set myself to go home."

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Today

• Game: Pirates vs. Atlanta Braves, 7:10 p.m., Turner Field.

• TV, radio: FSN Pittsburgh, WPGB-FM (104.7).

Pitching: LHP Zach Duke (6-4, 2.62) vs. RHP Kenshin Kawakami (3-6, 4.63).

• Key matchup: Atlanta star Chipper Jones is 9 for 19 in his career against Duke, with three doubles, and never has struck out.

• Of note: The Braves had lost eight of 11 -- and held to two or fewer runs in seven of those losses -- before busting out for 13 hits in an 8-7 victory yesterday against Milwaukee.

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"Once I saw that ball was in play, I'm going at it hard," Kata said. "I'm not turning to look if it gets through. I scored and had to ask someone what happened."

Houston added two in the eighth off Jackson and Jesse Chavez and took two of three in the series.

Coincidence or not, the Pirates are 5-14 when Wilson does not play, 21-15 when he does, and those who have replaced him at shortstop -- Vazquez and Brian Bixler -- have committed four errors, including Vazquez's second yesterday on a grounder directly at him in the second inning. More glaring, Vazquez has not shown the range to either side that one generally expects from a major league shortstop.

Russell pointed to Minute Maid's always-quick infield.

"I think Ramon does a nice job, for a limited amount of time out there," he said. "He's got instincts, a good glove, but it's a tough field for anybody."

Vazquez mentioned that, too, even as he acknowledged the lack of range.

"I didn't have that bad of a day," he said. "The first ball just confused me, like a knuckleball, and it ate me up. But I've played enough shortstop before. I'm not as fast as I used to be, don't cover the ground I used to, but I feel comfortable. I just try to be where the ball's going to be hit now."

These Pirates have issues far greater than backup shortstops, but it probably merits mentioning: This is the second year in a row management signed a free-agent utility infielder to a seven-figure salary even though he was below average at shortstop. Chris Gomez made $1 million last year, and the coaching staff was immensely reluctant to play him at that position. Vazquez, who spent just 45 games at shortstop for the Texas Rangers in 2007-08, is making $2 million this year, the same amount next year.

The finish overshadowed a bit of a rebound for struggling starter Ian Snell, who might have been in danger of losing his spot in the rotation.

"It's not a life-or-death start for Ian," general manager Neal Huntington said earlier in the day. "But there's no question we need to see some signs of advancement."

Snell delivered just his fifth quality start in 12 appearances, allowing three runs on eight hits over six innings. He struck out three, walked one and, in general, appeared more poised.

The key, according to Snell, was a review of films from his successful 2007 in which pitching coach Joe Kerrigan noticed his hands higher -- in front of his face -- to open the delivery.

"That's where he thinks my hands fit best," Snell said. "Everything felt easy coming out of my hand. Everything was down and around the plate."

"I thought Ian pitched well," Russell said. "He was around the plate all day, challenging hitters."

Houston lost its starter, Felipe Paulino, after 1 2/3 when he slipped on the mound and strained his right groin. That brought Russ Ortiz in emergency duty, and he would pitch 4 1/3 innings of scoreless relief.

The Pirates scored twice in the seventh to bring the 3-3 tie: Andrew McCutchen's bases-loaded groundout brought one, Nyjer Morgan's single into right another. The bases would get loaded anew, but Adam LaRoche bounced into a 3-2-3 double play to end the inning.