TUCSON, Ariz. -- The D-backs' roster situation became a bit clearer on Monday thanks to several roster moves.

The D-backs reassigned outfielders Chris Roberson and Gerardo Parra to Minor League camp.

Both of those moves were expected, but the club also announced that it had informed pitcher Travis Blackley that he would not make the team and allowed him to leave camp.

The left-hander was one of a handful of pitchers competing for the final four spots in the bullpen. He was out of Minor League options, so the club will need to place him on waivers if they have not already done so.

D-backs GM Josh Byrnes declined to comment on whether Blackley was on waivers or would be put there. Because he has been outrighted a previous time, Blackley has the right to refuse an outright assignment to the Minors if he should clear waivers. If he refuses it, he would become a free agent.

"He was disappointed," Byrnes said. "Thought he had a shot and threw well. He took it like anyone else would."

Byrnes said the team was leaning towards carrying 12 pitchers, even with Max Scherzer beginning the year on the disabled list. The plan is to activate Scherzer in time to start on April 14, the first day the team would need a fifth starter. Until then, they will apparently carry eight relievers.

Chad Qualls, Tony Pena, Scott Schoeneweis and Jon Rauch were bullpen locks coming into camp. With Blackley out of the mix, it's beginning to look like out-of-option relievers Yusmeiro Petit and Juan Gutierrez will make the club.

Petit has pitched well, though he had a rough first inning on Monday, and Gutierrez's arm is so intriguing to the D-backs that it doesn't appear they are willing to risk losing him on waivers.

That would leave two more spots, and to this point of camp, it seems Doug Slaten and Billy Buckner are the frontrunners, though Bobby Korecky and Leo Rosales are still on the roster.

Parra, who hit .301 at Class A Visalia and .275 at Double-A Mobile last season, certainly made an impression this spring. The 21-year-old hit .478 with two home runs and six RBIs in 23 Cactus League at-bats.

"I don't think we have a better position-player prospect in our organization," Arizona manager Bob Melvin said.

Parra will likely start the year in Mobile, but could move up quickly.

"He's one of those guys that plays up to the competition, which is a good thing," Byrnes said.