Less than three weeks later, on July 31, left-hander Brett Oberholtzer tossed seven scoreless innings in his first Major League start to beat the Orioles. Right-hander Brad Peacock turned in the best start of his young career a few days later by striking out 10 batters in a career-high seven innings at Minnesota.
Suddenly, the Astros are brimming with talented young arms, and the best might be yet to come. The Minor League system, which has been infused with talent via the Draft and trades the last few years, is overflowing with promise on the mound.
"It's something we've anticipated for a little while now," catcher Jason Castro said.
Strong starting pitching is nothing new to an Astros franchise that has featured some of the best throughout the years. Larry Dierker, J.R. Richard, Joe Niekro, Nolan Ryan, Mike Hampton, Mike Scott and Roy Oswalt had dominant seasons with the Astros, but a new arms race is here.
Cosart, 23, is 1-0 with a 1.36 ERA in five starts, allowing 25 hits in 33 innings. He's the first Astros pitcher in history to begin his career by going at least five innings and allowing two or fewer runs in each of his first five starts.
Meanwhile, Oberholtzer, 24, is the first pitcher in franchise history to throw seven or more scoreless innings in each of his first two starts. What's more, he's the first Major League pitcher since Philadelphia's Marty Bystrom in 1980 to achieve that feat.
As a result of the performances from Oberholtzer and Peacock, both of whom were called up to make spot starts last week, the Astros are going with a six-man rotation that includes 22-year-old Jordan Lyles and 25-year-old lefty Dallas Keuchel. Youth is served.
"If you're going to have a surplus, that's a good area to have one, because we all know that pitchers get injured more than position players, and you never know what you're going to get until they perform on this stage, at this level," Astros general manager Jeff Luhnow said. "Sometimes, it takes two or three trips to the big leagues to figure out what the player is going to be."
Oberholtzer and Peacock are prime examples. Both are in their third stint with the Astros this year and were met with mixed results their first two times in Houston. Peacock began the season in the rotation and was moved to relief after struggling, and Oberholtzer was a career starter in the Minor Leagues before finally getting to start with the Astros after being used in relief.
"There's a lot of competition, and it's fun," Oberholtzer said. "For me, I like to feed off of that. I like to feed off the guys pushing one another. Some guys maybe take advantage of it, and some guys won't. For me, I like to work hard day in and day out and push myself and push others, and hopefully that will motivate others to go out there and bring winning back to this organization."
Nine of Houston's Top 20 Prospects as ranked by MLB.com are pitchers, led by 2013 No. 1 overall Draft pick Mark Appel and 2012 first-round pick Lance McCullers, who has 115 strikeouts in 100 2/3 innings at Class A Quad Cities. Hard-throwing right-hander Mike Foltynewicz is 5-2 with a 2.71 ERA in 19 games (13 starts) at Double-A Corpus Christi.
Right-hander Asher Wojciechowski could be headed to Houston soon after going 9-5 with a 2.67 ERA in 23 games (19 starts) between Corpus Christi and Triple-A Oklahoma City. Then there's Corpus Christi right-hander David Martinez, who has the best winning percentage in the Minor Leagues with a 14-2 record. He leads the Texas League with a 2.02 ERA.
Brady Rodgers (9-6, 5.34 ERA at Class A Lancaster), Vincent Velasquez (8-4, 3.38 ERA at Quad Cities), Jake Buchanan (11-4, 2.41 ERA between Corpus Christi and Oklahoma City) and Nick Tropeano (6-7, 4.34 ERA at Corpus Christi) are on the rise. Recent Draft picks Adrian Houser, Kent Emanuel and Andrew Thurman have high ceilings as well.
And don't forget Alex White, who was acquired from the Rockies last December. He made the rotation out of Spring Training before undergoing Tommy John surgery and missing all of 2013. He should return next year at 25 years old.
"The fact we've got young arms in the rotation right now and more coming and waves of them coming through the Minors, that means we're going to have plenty of good arms to choose from going forward," Luhnow said. "That's where it all starts."
The Astros have created enough competition that pitchers who aren't getting the job done at the Major League level next year could be pushed aside in favor of someone else. They've put themselves in position where they won't have to plug holes with veterans on Minor League deals or try to fill gaps like they did in 2012 with Fernando Abad, a reliever who went 0-6 in six starts.
"That's how you build a winning ballclub, is by having guys compete for jobs, compete with one another and compete for the ultimate goal, which is to win," Oberholtzer said. "If that doesn't fuel your fire, you're in the wrong game. That's what sports are about. We're in the entertainment business, and there's nothing that's going to be given to you. You have to earn it and not take anything for granted."