KISSIMMEE, Fla. -- On a back field at the Astros' Spring Training complex, a large man grabs a black bat and starts thwacking deep fly balls to right field. His fierce uppercut swing propels the ball high into the Florida air, out of sight.

This is what the Astros expect to see from Jack Cust this season -- albeit in a game setting, not a batting-practice session.

But through 14 Grapefruit League at-bats over five games, Cust has yet to log a single hit, let alone a homer. And at some point, the Astros will have to determine whether Cust's power potential is worthy of an Opening Day roster spot.

"Often, it's hard to evaluate power guys early in spring, because they may not show what you need to see, and that's frustrating for him and probably for us," general manager Jeff Luhnow said. "One thing that's clear is Jack Cust takes good at-bats. He lays off marginal pitches, he lays off bad pitches. His timing and stroke are not to the point yet where he's done the things that I know he can do. And so at that point, it becomes a question mark: Do you know that's coming and do you take a chance keeping him on the roster assuming that's going to come? Or do you explore other options for those extra spots?"

If the 33-year-old Cust can perform at a level similar to his career norm, then he brings this Astros offense two things it was clearly lacking last year -- power and walks. Houston hit the second-fewest home runs (95) and drew the fewest walks (401) in all of baseball last season.

Cust, on the other hand, has averaged about one home run for every 20 at-bats in his career, and he's drawn a walk in 17.2 percent of his career plate appearances, according to baseball-reference.com. So that's his appeal, even though he's struck out in 31.7 percent of his plate appearances.

But Cust is coming off an awful 2011 in which he was cut by the Mariners in August after batting just .213 with three homers and 23 RBIs in 270 plate appearances over 67 games. That was also the first year of Cust's Major League career, which dates back to 2001, in which he didn't log a single inning in the field.

"Just DHing was a little difficult," he said. "When I was in Oakland, I'd play half outfield, half DH. When you're not hitting, sometimes it's nice to go out in the field and have something else to think about, instead of having an at-bat, going to look at the video and anticipating so much."

That's why Cust is excited about this opportunity to compete for a corner outfield job with the Astros.

"It's another opportunity to put the uniform on and play baseball," Cust said. "There's nothing like coming out here and being able to compete."

But between his struggles at the plate in the early going and his inability to play in the field yet because of right elbow tendinitis, Cust's competition isn't going particularly well.

Still, he's encouraged and manager Brad Mills is encouraged by the direction his at-bats have taken. Cust drove a ball to the opposite field (and into a glove) in Monday night's loss to the Yankees, and he said he feels his timing is coming along.

"It takes me a little while to get going -- just getting the timing and stuff.," Cust said. "As I've gotten older, it's taken a little bit longer. But [Monday], I think I found something that will help me be a little more consistent."

The Astros will continue to give Cust consistent at-bats, hoping something will click and he'll turn that power potential into reality.

"Some of these guys tend to really blossom as it gets warmer and they get into the season and have a more regular routine," Luhnow said. "So it's challenging."

Cust is on a one-year contract for $600,000 with a club option for 2013 -- when the club shifts to the American League and will need a DH.

But that contract is not a guaranteed deal, so Cust has to earn his way into the Opening Day outlook.

"I always feel like I'm competing for a spot," Cust said. "My career has never been a sure thing. Even when you feel like you do have a job, it still can be taken away. I learned that in Oakland, where I did well and they still sent me back to the Minor Leagues after three pretty good years [from 2007-09, when he averaged 28 homers]. So it keeps you hungry. Baseball's hard enough without all the other stuff that you can't control. You just have to control the things you can control, which is in the batter's box and on the field."

Cust's bid to control his end of the bargain here in camp continued Tuesday morning, one big swing after another.