"It's not critical," Cooper said Sunday. "I think most managers would tell you they'd like to have somebody out there who can turn the [switch-hitter] around to the other side or [for] that tough, tough left-handed hitter, he can kind of go in and be able to shut him down.
"You'd like to have a left-hander if at all possible. But having said that, if [we're] coming down to the 28th of March and we've got 12 right-handed pitchers, we've got 12 right-handers."
Most managers would consider a lack of lefties a hindrance. In a division where night after night, a team faces tough left-handed hitters like Milwaukee's Prince Fielder or Cincinnati's Adam Dunn and Ken Griffey Jr., it might be crucial.
Cooper, however, is optimistic the Astros will find an answer one way or another.
Either one of the four lefty reliever candidates -- Mark McLemore, Stephen Randolph, Josh Muecke or Wesley Wright -- will win the job, or one of the various right-handed options will have to be effective against left-handed hitters.
"We do have a couple of [right-handers] who we think will be able to do the job," Cooper said. "We think [Doug] Brocail can do that. [Oscar] Villarreal will be fine with that. I think [Chris] Sampson, if he's not in the rotation, will be fine with that."
Among the lefty candidates, McLemore may have the inside track.
The 27-year-old was 3-0 with a 3.86 ERA in 29 appearances with the Astros last season. He was very effective against right-handed hitters, holding them to a .204 (20-for-98) batting average. But he struggled against left-handed hitters. Lefties batted .419 (18-for-43) with a .480 on-base percentage against McLemore.
"If he shows that he can be effective against lefties, he's another guy that would be thrown into the mix," Cooper said.
Randolph hasn't shown the consistent control Cooper would like to see. But we're barely into March, and as Randolph has a plus arm, he will get every chance to claim the role.
Wright, 23, has potential, but might not be ready to make the jump to the Major Leagues. Muecke, like Randolph a non-roster invitee, won nine games for Double-A Corpus Christi last season. He can start or relieve and has a very good arm.
One lefty who won't be thrown into the mix is Wandy Rodriguez. The Astros have no plans to move him from the rotation.
"I think he's going to give me 200-plus innings," Cooper said. "We're not considering him [for the bullpen]. Wandy's a guy I think has a chance to be a real good starting pitcher."
Other righties who might climb into the picture include Felipe Paulino, Fernando Nieve, Chad Paronto, Mike DeJean and Brian Moehler.
The prospective candidate's chances would improve if he masters just two things: Not walking a lot of batters and retiring left-handed hitters consistently.
"If it happens to be a lefty, fine, but if he's a righty and he's effective against them, we'll go with him," Cooper said. "What did we have last year? We had one [lefty] Trever Miller. And that's what we'll do here. If we don't have it, we don't have it."
Jim Molony is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.