HOUSTON -- The White Sox have dropped 15 games by one run this season, including six of their last 10 losses.
After their latest close defeat -- 5-4 to Houston on Sunday -- they were searching for reasons why they can't seem to do the little things it takes to win such games.
It was their third straight one-run loss in this series.
"When you lose by one run every game, you always go back to that one inning when we did not get things done," Chicago's Adam Dunn said. "Pretty much every one of our losses you can point a finger at whether it's first inning, fourth or sixth.
"Usually there is one inning when we have the chance to break the game open with a blooper, anything, and we aren't getting those."
On Sunday that inning was the seventh. Dayan Viciedo led off with a triple and scored on a one-out single by Jeff Keppinger that got Chicago within 3-2 and chased Houston starter Dallas Keuchel.
He was replaced by Jose Cisnero, who was greeted with a single by Gordon Beckham before pinch-hitter Conor Gillaspie walked to load the bases. The White Sox came up empty when Cisnero struck out Alejandro De Aza before Alexei Ramirez grounded out to end the inning.
"You are looking at that seventh inning, and you want something to happen," manager Robin Ventura said. "Once you get the bases loaded, you put them in a vulnerable spot. You figure you are going to get at least another one out of that, and you don't. It's frustrating."
Jason Castro homered for the second straight game, and Matt Dominguez hit a three-run double to help the Astros to their fourth straight victory.
Dominguez put Houston on top 3-0 with a double in the second inning, and Castro hit a two-run shot to make it 5-2 in the seventh.
The left-handed Castro hit his first career home run off a left-hander on Saturday night when he connected off John Danks, and made it two when he hit a slider from Matt Thornton on Sunday.
De Aza tripled and scored in the sixth, and Viciedo tripled and scored in the seventh to cut the lead to 3-2. De Aza added a two-out, two-run homer off Jose Veras to make it 5-4 in the ninth before Ramirez grounded out to give Veras his 14th save.
Keuchel (4-3) yielded four hits and two runs in 6 1-3 innings for the win.
Hector Santiago (2-5) allowed five hits and three runs with eight strikeouts in 5 1-3 innings.
"You go out there and play good games, it's not like we are getting blown out," Santiago said. "It's one-run games. If we get one big hit, it's a different ballgame. If we got a hit with the bases loaded, it changes the game. We haven't been able to get that clutch hit that we need to turn things around in the game. You keep battling and try to keep us in the game, and I feel like we are doing that right now, but we need to get that one big hit."
The AL-Central-worst White Sox have dropped four straight overall and 12 of their last 13 road games to fall 10 games under .500 (28-38) for the first time since May 7, 2011. They have had trouble scoring in this span and have been outscored 71-41.
"Offensively, we are not getting it done," Dunn said. "If I could sit here and put a finger on why (I would), but I can't. For once, I am speechless. I don't know why our offense is sputtering.
"We have the talent. We have everyone in place. We just aren't producing."
Chris Carter singled with one out in the second before Santiago issued consecutive walks to load the bases. Dominguez cleared the bases with a double, which skidded down the left field line, just out of reach of a diving Jeff Keppinger to make it 3-0. He advanced to third on the throw home.
Brandon Barnes robbed Viciedo of a hit when he raced up Tal's Hill in center field and made an over-the-shoulder grab before falling and rolling into the wall to start the second inning.
The White Sox got their first hit the next batter when Dunn singled. But Keuchel retired the following nine hitters, with Chicago's next runner coming when Keppinger walked with one out in the fifth.
De Aza tripled to start the sixth inning, and Chicago cut the lead to 3-1 when he scored on a sacrifice fly by Ramirez.
NOTES: Houston's game on Saturday night ended when Veras picked off Jordan Danks at second base. It was the first time in franchise history that a game was ended by an Astros pitcher picking off a runner, according to information provided by the team from the Elias Sports Bureau. ... The series wraps up on Monday when Houston's Bud Norris opposes Jose Quintana. Norris has a 2.28 ERA in eight starts at home this season. ... White Sox OF Dewayne Wise, on the disabled list with a strained right hamstring, went 1 for 3 with a triple in a rehabilitation game with Triple-A Charlotte on Saturday.