First-year manager Bo Porter will have to be creative this spring when it comes to finding enough innings to properly evaluate all the candidates for the starting rotation. Luhnow said right-handers Bud Norris, Lucas Harrell and Jordan Lyles are locks for the rotation, with Humber having a leg up for the fourth spot.
That will leave five pitchers battling for the final spot -- White, Ely, Keuchel, Cosart and veteran Edgar Gonzalez, who signed a Minor League contract with a Spring Training invite.
"I think Harrell, Norris and Lyles, it's their job to lose at the top of the rotation," Luhnow said. "We're talking about the other two spots and there's lots of competition for it. Humber has obviously got a proven track record, so he'll probably have an edge over the other guys, but Ely had a terrific Minor League season, White has definitely got the stuff, and Keuchel showed last year he can be, at times, competitive. He just needs to improve his consistency."
The Astros claimed Humber off waivers from the White Sox in November and promptly signed him to a $800,000 contract for this season with a club option for $3 million for '14. The Texas native, who pitched at Rice University in Houston, threw a perfect game last year, but was inconsistent at the end of the season.
White, 24, came to the Astros in December in a trade with Colorado, where he was 2-9 with a 5.51 ERA last season in 23 games (20 starts). He split the season between Colorado and Triple-A Colorado Springs, where he went 3-4 with a 3.71 ERA.
Ely, 26, worked the majority of last season pitching at Triple-A Albuquerque in the Dodgers organization, going 14-7 with a 3.20 ERA in 27 starts. He has made 25 career Major League appearances in three seasons for the Dodgers, who traded him to the Astros in December.
Keuchel, the only left-hander in the mix, made his Major League debut last year and had an up-and-down rookie season. He wound up going 3-8 with a 5.27 ERA in 16 starts, but will have to be more consistent to stick in the rotation.
Then there's Cosart, one of the team's top pitching prospects. The Houston area native went 6-7 with a 3.30 ERA in 21 games (20 starts) combined at Double-A Corpus Christi and Triple-A Oklahoma City last year and possesses one of the best fastballs in the system.
"Cosart will be in the mix, but it would be a surprise for me if he made the club out of Spring Training," Luhnow said. "Stranger things have happened, but I feel like he needs a little more seasoning. He's not far away. I wouldn't be surprised if all those names mentioned are pitching in the rotation at some point in 2013."
The Astros had 11 different pitchers make starts in 2012, led by Harrell (32), Norris (29) and Lyles (25). Keuchel made 16 starts and Gonzalez made six, going 3-1 with a 5.04 ERA after being signed out of the Mexican League.