PHOENIX -- The D-backs will be without their leading hitter for at least the next two weeks, as outfielder Chris Young was placed on the 15-day disabled list on Wednesday with a right shoulder contusion.

Young injured the shoulder crashing into the wall during Tuesday night's loss to the Pirates. X-rays showed no breaks, and an MRI performed on Wednesday morning showed a deep bruise in the AC joint and a small tear in the ligament there.

In the best-case scenario, Young will be back in 15 days, but at this point there's no way to know.

"I don't think you ever know," general manager Kevin Towers said. "I hate to ever put timelines. All I know is [that] C.Y., when he's ready, is going to want to be back in the lineup."

In fact, Towers said they had to talk Young into going on the DL, a place he's never been since coming to the big leagues in 2006. It wasn't until the doctor said he could worsen the injury that he decided it was the best course of action.

"I don't want to go out there and make it worse, and the next thing you know, you're missing the entire season over it," Young said. "[I'm] just trying to do the right thing and get it healthy."

Infielder Cody Ransom was called up from Triple-A Reno to take Young's place on the roster.

A.J. Pollock, who was called up from Reno on Wednesday when Geoff Blum was placed on the DL, got the start in center in place of Young.

Young has been the D-backs' best hitter this year. He is third in the National League in hitting, with a .410 mark, and is second to the Dodgers' Matt Kemp in home runs (five) and slugging percentage (.897). His loss leaves a big hole in the lineup, especially with right fielder Justin Upton limited by an injured left thumb.

"He was one of the hottest bats in the National League, and to lose him for at least the next couple of weeks will be difficult," Towers said. "But we have to deal with it. Hopefully, we'll be able to get him back sooner rather than later."

"It's one of those deals [where] you have to move on and find a way," manager Kirk Gibson said. "You can't be discouraged. Things happen along the way, and you stand up to that challenge. It's not how we planned it out, but you sign in, and you're either in or out."

Ransom was hitting .294 with a pair of doubles and two home runs for Reno. He appeared in 12 games for the D-backs last year and hit .152.

No trip to disabled list for Upton just yet

PHOENIX -- Chris Young and Geoff Blum went on the disabled list on Wednesday, but Justin Upton did not.

Whether the right fielder eventually ends up on the shelf depends on how his ailing left thumb responds to treatment.

"That's just day to day right now," general manager Kevin Towers said.

Upton was out of the starting lineup on Wednesday for the second straight game, but he did appear as a pinch-runner in the ninth.

Upton injured the thumb when he jammed it sliding into second base during the April 8 game against the Giants. An MRI was performed, and fluid was drained from the thumb on Tuesday night.

"[It's] probably a little bit better today, hopefully [it will be] a little bit better tomorrow," Towers said. "Hopefully, he'll be able to avoid the DL. If not, we'll have to deal with that, too. Hopefully, he'll be fine the next two or three days, and we'll be able to get him back in the lineup."

Though Upton had played through the injury without complaint up until the last couple of days, it clearly was affecting him at the plate, as he is hitting just .212 with two doubles and no homers.

Pollock called up, makes first big league start

PHOENIX -- When Triple-A Reno manager Brett Butler gave outfielder A.J. Pollock the news that he was headed to the big leagues, Pollock at first did not believe him.

"I thought it was a joke," Pollock said. "He kind of half told me. I don't know if he was trying to build up the drama or something. When I realized it was true, I started getting some adrenaline going, and I was pretty pumped."

Pollock will take the place of Geoff Blum, who was placed on the 15-day disabled list on Wednesday with a strained left oblique muscle.

With outfielders Chris Young and Justin Upton out of the lineup with injuries, Pollock did not have to wait long to make his Major League debut, as manager Kirk Gibson had him in Wednesday's starting lineup, batting seventh and playing center field.

"It's pretty awesome," Pollock said of seeing his name in the lineup. "I was pretty pumped. I'd rather just get thrown into the mix as opposed to the buildup, so I think that's going to help me, and I'll just go out there and try to help the team win. They've got a good team here already, and as long as I'm playing my role and doing my part, then we'll be fine."

Though this is Pollock's first taste of the Majors, the team kept him around until the end of Spring Training so he could play in a pair of exhibition games at Chase Field.

Gibson said that the idea was to give him a taste of what it's like playing center in the ballpark should he be needed in a situation just like this one.

"Doing that stuff, kind of being around the field here, getting comfortable, absolutely helped 100 percent," Pollock said.

In 12 games for Reno, Pollock was hitting .340 with six doubles and an .839 OPS.

"He's a pretty complete player," Gibson said. "He's a good outfielder, he throws the ball well, he runs the bases well, he's smart, he swung the bat well in Triple-A. I'm glad we kept him here through the end so he got to play in this stadium. This is when that pays off. It's still going to be overwhelming for him, his first day in a true big league game. He's well prepared for today, and there's a lot on his shoulders. We think he's got good character."