TUCSON, Ariz. -- Justin Upton's numbers haven't been stellar this spring, but the Diamondbacks' prize 19-year-old prospect has been far from a disappointment.

And despite Bob Melvin deciding to reassign the center fielder to Class A Visalia Oaks on Tuesday, the manager said he couldn't be happier with the progress Upton made in terms of his approach to the game.

"I think it was great at 18 years old he was in a big-league camp and had some success," Melvin said, referring to last spring. "... But he's done even better this camp. Rarely do you see a guy of his age, both in the clubhouse and on the field, handle himself the way he does. This guy is on the fast track."

The fast track is a relative term. While the D-backs stress patience to Upton, who was 0-for-3 in a B game Tuesday and hit just .222 in the Cactus League, their outfield depth means there is no rush on bringing up the first overall pick in the 2005 draft.

Melvin said it's never good to put a date on when a player will break on to a Major League roster, "but boy, at 19, you don't see kids like that handle themselves at the big-league level like he does. I would never say never, but this year could be a stretch."

And that doesn't seem to bother Upton.

"I know where I'm going to start," he said. "I can be optimistic and say, 'I hope to be in the big leagues this season,' but I'm just going to go out and play. It gets tough hearing 'You're only 19' all the time because there's nothing I can do about that. But I'm more than happy working on those things I can do something about right now."

Melvin wasn't the only one who noticed the mature approach Upton took this spring.

Tony Clark, Arizona's 35-year-old first baseman, said a slow approach for Upton's MLB progression is best for everyone.

"He's built like a man and the things he does on the field are things men do, but you have to understand he's 19," Clark said. "But I'm excited about the things he can do. There aren't a whole lot of young black players and we have one of them. It's going to be fun to watch what he does."

Davis struggles: Doug Davis got roughed up in Tuesday morning's B game with the White Sox. The lefty allowed 10 hits, five earned runs, a homer, walked four and struck out two in what amounted to one inning of work.

The B game format had Davis on a per-inning pitch count. He came out from the dugout for four innings of work, but the D-backs actually just retired three White Sox hitters in those four innings.

"The results were terrible, obviously, but I got my work in and I felt healthy," Davis said. "I fell behind a few batters and that's what really hurt me."

Owings makes his pitch: Micah Owings, a non-roster invitee fighting for the team's last roster spot, was impressive in three innings of work Tuesday against the Cubs. He allowed one hit, one walk, no runs and struck out four.

Owings has now pitched seven innings this spring, allowing just one earned run and four hits while striking out eight and walking three batters.

Roster moves: Including Upton, nine Diamondbacks were involved in moves on Tuesday. Upton, catcher Wilkin Castillo, and right-hander Adam Bass were reassigned.

The six players optioned were: infielders Emilio Bonifacio and Danny Richar, outfielders Carlos Gonzalez and Alex Romero and pitchers Evan MacLane and Jailen Peguero.

MacLane had been battling for the fifth spot in the rotation while Gonzalez hit .429 through 12 Cactus League games.

"Carlos Gonzalez is going to be a heck of a player," Melvin said. "This guy has a chance to be an All-Star. Bonifacio really opened up some eyes this spring. ... Evan MacLane did some good things for us, too. We just didn't have the innings to give him."

Byrnes' big bat: For the second straight game at Tucson Electric Park, Eric Byrnes led off the the bottom of the first with a homer into the right-field bullpen. Sunday, he did so on the second pitch off Padres starter Jared Wells. Monday's homer was a first-pitch-swinging home run of Cubs starter Wade Miller.

They were the first two homers of the spring for Byrnes.

Bumps and bruises: Lefty Doug Slaten shouldn't miss much time after taking a ninth-inning line drive off his left forearm in Monday's win over the Rockies.

"Probably a couple days. Not as bad as we thought," Melvin said. "With the day off [Wednesday], we'll re-evaluate after that."

Melvin said the liner didn't hit bone and just left a bruise.

First baseman Conor Jackson, who was shaken up for a moment Monday in fielding practice after a ball took a bad hop and struck him in the temple, was in the starting lineup Tuesday.

RJ update: Melvin said he likely won't decide on when Randy Johnson will throw another batting practice session until after Wednesday's off-day.

Johnson, recovering from offseason back surgery, threw batting practice on Saturday and said everything feels fine. Melvin said the team hasn't encountered any set backs with Johnson this spring.

The timetable for Johnson joining the team during the regular season remains a tentative "mid-, maybe late April," according to Melvin.

"Typically in something like this, you do get some setbacks," Melvin said of the back surgery. "Now whether that's a day or two or three, that still fits in the time frame of middle to late April."

Plans for the off-day: Clark, a former college basketball player, said he plans to spend Wednesday with his wife studying up on NCAA tournament brackets.

"I haven't even looked at them yet," Clark said. "I told my wife -- she coaches high school basketball -- I'm bringing home some sheets Wednesday and we're going to go through them together."