The loss dropped the Pirates to below .500 for the first time this season and prevented them from securing their first home series win of the season.
"I let it get away," said a palpably disgusted Burnett afterward. "I'm really frustrated right now."
Burnett entered the game in the sixth after an early exit by Pirates starter Jeff Karstens forced manager John Russell go to the 'pen early. Craig Hansen pitched a scoreless fifth and handed the ball to Burnett with the game still tied at 3.
Burnett got two quick outs, both against right-handed hitters, which have pestered the lefty in the past. But Burnett couldn't close it out. He allowed a two-out double to the left-handed-hitting Michael Bourn and a walk to Miguel Tejada, after getting ahead in the count, 1-2.
"He had Tejada where he wanted him and let him slip away," Russell said.
That brought up the switch-hitting Berkman, who obviously chose to swing from the right side. With the count even at 1-1, Burnett threw a slider in the dirt. Berkman swung and missed. Burnett went back to the slider on the next pitch, intending for it, too, to be low. However, he left it hanging, and Berkman sent it sailing for his second homer of the season.
The three-run shot snapped a streak of 8 1/3 scoreless innings from the Pirates' bullpen, which entered the game with the fourth-lowest ERA in the Majors.
But while Burnett was tagged with his first loss of the season, it didn't help that Karstens was unable to make it past the fourth in what was his first start of the season. The righty hadn't pitched in a game since March 31, as he was the skipped in the rotation last week when his scheduled start was rained out.
His results would suggest rustiness, which Russell did imply played a role, but Karstens started sharply. A 1-2-3 first inning seemed promising, but Karstens' command dipped and his pitch count elevated from there.
"It felt like forever since I had been out there, but I felt good," said Karstens, who won the fifth-starter job during the final week of Spring Training. "I felt like the ball was coming out of my hand really well in the first inning. The first inning, I was a little amped up. I got lax then and started guiding the ball."
Though he was given three early runs by his offense, Karstens handed all three back by allowing single runs in the second, third and fourth innings. He walked five, one of which scored, surrendered a homer to Houston's Hunter Pence and allowed four hits. His pitch count sat at 87 at the end of four innings.
"It wasn't because I hadn't been out there," Karstens said of his control issues. "It was because I wasn't throwing the ball over the plate. We threw bullpens in between and did everything to prepare myself. It's just a matter of getting back out there and executing."
Karstens, who was using a retooled over-the-head delivery for the first time in a game situation, said that the mechanical adjustment played no role in his struggles. In fact, it's a motion that he plans to stick with moving forward.
Though Karstens labored, the Pirates' offense supplied him with some run support early against Astros starter Russ Ortiz.
Nyjer Morgan doubled and scored on a wild pitch in the first, before first baseman Adam LaRoche doubled home another run later in the inning. It was the duo which provided the majority of the offensive fireworks all series.
After scoring in the first, Morgan showcased his speed when he legged out a second-inning RBI triple that put the Pirates up, 3-1. Morgan later singled in the seventh, leaving him a home run shy of hitting for the cycle.
"I was trying to do my thing and get on base," Morgan said. "It's just too bad we couldn't get the win."
As for LaRoche, he continues to show signs that his April woes are a thing of the past. With two doubles on Thursday, LaRoche finished the series 7-for-12 with five extra-base hits and four RBIs. His season average stands at .294.
"I think it's more of a story for you guys than it is for us," Russell said of LaRoche's past early-season struggles. "Adam had a good spring and we saw a lot of progress with how he was approaching the ball. Unfortunately, in the past he's struggled early in the year. But we're not putting a lot of emphasis on it."
Two of those first three runs scored with two out, but the Pirates lacked that two-out RBI hit in the innings that followed. They had at least one baserunner on in each of the final five innings, and two on with less than two outs in the sixth and seventh. None reached home.
"We're going to have to start coming up with some big hits," Russell said. "You see good signs, but our offense needs to start clicking as a unit instead of just a couple of guys here and there."
Though their hits were of no consequence to the outcome, both Andy LaRoche and Jason Jaramillo each had notable singles in the game. Jaramillo's fourth-inning single was the first hit of his Major League career, while LaRoche snapped an 0-for-18 season start with his sixth-inning single.