Seth Maness will be in the 'pen and could fill a long-relief role, if needed. Randy Choate returns as a lefty specialist. Non-roster invitee Pat Neshek has done all he needs to in order to secure a Major League job, as well.
That seventh spot would belong to Jason Motte, but the right-hander will begin the season on the disabled list as he finishes his Tommy John rehab. That means that the four remaining pitchers in camp -- Jorge Rondon, Keith Butler, Sam Freeman and Scott McGregor -- who are not competing for a starting job are vying for that last opening.
Butler and Freeman each have previous Major League experience. McGregor, a recent addition to big league camp, has been groomed as a starter, so there would be a transition in role should he be called upon to pitch out of the 'pen.
The most impressive this spring, though, has been Rondon. He's gotten into some trouble -- eight hits and two walks in 6 1/3 innings -- but he has pitched himself out of every one of those jams. In six appearances, Rondon has struck out six and not been scored upon.
"I think it's been a very, very good spring for Jorge," manager Mike Matheny said. "We approached him with a simplified approach, and he embraced it and did a great job of trying to figure out how to make that work. Our instructions to him were: 'You can help us with your stuff, but you're going to have to be in the strike zone. That's all there is to it.'
"We were very pointed with our instructions. He went to work that day and got up on the mound and took a simplified approach and has continued to work on it. He definitely has done a real nice job with making those adjustments."
Rondon, 26, has made a methodical climb through the organization's farm system since he was signed out of Venezuela in 2006. In '13, he led Triple-A Memphis with 51 appearances. He posted a 3.06 ERA, but he walked nearly as many batters (37) as he struck out (42) in 67 2/3 innings.
Of these four pitchers battling for a big league roster spot, Freeman is the only lefty. Matheny said he has not ruled out carrying three left-handed relievers, but that "it's a matter of who is going to make quality pitches, not left- or right-handedness at this point."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.