What the Padres didn't count on, what they probably never allowed themselves to think, was that Oswalt, whom they had defeated Opening Day at PETCO Park, wouldn't be their biggest cause for annoyance at Minute Maid Park.
It was actually an Astros' offense that, depending on how you crunch the numbers, was actually worse than the Padres' anemic bunch, though that wasn't readily apparent here on a warm night.
The Astros scored early and often Monday, rolling up a five-run lead in the first inning before Justin Germano got an out as Houston rolled to a 10-3 victory before a crowd of 28,600, who probably couldn't care less Oswalt's ERA is still 6.00.
"Chalk this one up," said Padres manager Bud Black following the loss. "to a bad night."
A bad night indeed, on what has become a thorny road trip.
The Padres are now 1-3 on a five-game road trip through the Southwest that has proved to be anything but hot for a pitching staff that has allowed over nine runs on already three occasions, as its ERA has climbed from 3.10 on April 17 to 3.88 over just four games.
For what it's worth, the Padres (9-11) got to Oswalt for three runs on six hits, including solo home runs by Jim Edmonds, his first as a Padre, and an opposite-field shot to left field by Adrian Gonzalez.
Given the rate the Astros -- who entered the game hitting .227 as a team -- scored runs on Monday, especially early, that was no small feat.
Germano, who began the season with 13 scoreless innings, opened the game by issuing four consecutive balls to leadoff hitter Michael Bourn. Then came consecutive singles from Kaz Matsui and Miguel Tejada for a 1-0 lead without an out.
Lance Berkman then launched a three-run home run to center field before Carlos Lee reached on a walk and former Padre Geoff Blum sent him racing to third base. After Hunter Pence doubled in a run, Germano got his first out of the game when another former Padre, Brad Ausmus, reached on a fielder's choice.
"Fortunately, he walked me on four pitches, and that's great for a hitter. I'll take it all the time," Bourn said. "That got things going tonight. The people behind me, as you can see, Tejada, Berkman and Lee, came to hit. When they come to hit, it's hard for a pitcher to get in a groove. They know how to work the count, so what can you really do?"
In Germano's case, not a whole lot, as he allowed 10 runs on 10 hits.
"When he missed, he missed in the middle," Black said. "It looked to me that when he tried to go to either side of the plate, the ball kept coming back over the middle. ... It's rare. He starts the game with four balls. That's not Justin-like."
Germano (0-2) knew early on that something wasn't right with his command. The worst part, though, was there wasn't much he could do to fix it, as Tejada would hit a two-run home run in the second inning as the Astros built a 7-1 lead after two innings.
"To walk him on four pitches, I didn't feel locked in," Germano said. "I had a couple of at-bats with guys where I felt better, but it's tough. You've got to bear down and try to keep the ball down. I was struggling to do that, too."
Had the start been different Monday, the ending might have been as well, as the Padres' hitters felt like they had a good plan at the plate against Oswalt, who had allowed left-handed hitters to bat .410 against him entering the game.
Sure enough, Oswalt allowed a home run to Edmonds with one out in the second inning and a shot to Gonzalez to start the sixth inning. All told, the Padres had six extra-base hits, five off Oswalt, including two doubles by leadoff hitter Brian Giles.
"We had some good rips at [Oswalt], but nothing fell for us," Black said. "He was pitching with a big lead and threw strikes. We battled him, but it wasn't easy with a big lead."
For the second time in a week, long reliever Wil Ledezma came up big for the Padres, essentially saving a taxed bullpen, ravaged after a lost weekend against Arizona, from another night of work after Germano departed after 3 1/3 innings.
Ledezma, who tossed five scoreless innings in the 22-inning loss to Colorado on Thursday, kept the Astros off the scoreboard for 3 2/3 innings, allowing three hits and two walks with two strikeouts. Unlike the Colorado game, Ledezma had an idea he might be the pitcher to enter the game when Germano was getting into trouble.
"I felt great," Ledezma said. "This was the first time I was all ready. I knew when he got in trouble, I was in."
The Padres hope that Tuesday's game doesn't involve their bullpen, as National League Cy Young Award winner Jake Peavy gets the start, fresh off throwing eight scoreless innings in the 22-inning game. This is especially important for a team that has lost five of its last six games.
"When things aren't going good for you, these things happen," Giles said. "You've got to keep these ruts to a minimum."
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.