PEORIA, Ariz. -- Miguel Montero has seven years of professional baseball under his belt, but he's probably never had a spring as challenging as 2008.

After spending his first full season in the big leagues last year, Montero had been looking forward to his second appearance on an Opening Day roster and a season of continued growth backing up Chris Snyder behind the plate. But a broken finger suffered while playing winter ball in December has kept Montero out of Cactus League action to date and made him far too familiar with the twiddling of his thumbs.

"It's a little tough," Montero said. "When you're used to doing your stuff, you're used to playing baseball, and being in this situation when you're not allowed to do any type of baseball activities, I feel kind of bad. You don't feel like you used to, especially me, playing winter ball all the time, playing all year round. Just sitting around and lifting or whatever, it's a little tough."

The toughest part of it for Montero may be facing the fact that time has probably run out on his chance to be ready for Opening Day. He and Chad Tracey are perhaps the biggest health concerns for the D-backs. The two projected 25-man-roster men are likely to start the season rehabbing.

"It's probably going to be difficult for either one of them to start the season with us," manager Bob Melvin said on Wednesday.

Though Melvin is still waiting to get medical clearance before slating his backup catcher to resume baseball activity, Montero is optimistic that he'll be able to ease back into things beginning this weekend.

"I'm going to start playing catch and hitting off the tee and soft toss on Friday," Montero said. "I'll start throwing a little bit, a nice slow program."

Even if he can't make up for lost time and make his way onto the roster by Opening Day, Montero's eventual place on the 25-man roster is secure, as soon as his health allows it. He won Melvin's confidence with a solid wire-to-wire season, making the difficult adjustment from being an everyday player in the Minors to a backup big leaguer.

"Last year was the first year he had to play off the bench," Melvin said. "He did a great job for us as far as pinch-hitting and late at-bats. It seemed like his late-game at-bats were better than his early-game at-bats. I need to get him in there, but when you have a guy back there who's doing real well in Snyder, it's tough to get him out of there."

Spring Training
News and features:
Multimedia:
• D-backs voice Munn on Unit, Upton  400K
• Gilbert on Unit's debut  400K
• Young on commentary  400K
• D-backs on expectations  400K
Spring Training info:
MLB.com coverage  |  Schedule  |  Ballpark  |  Tickets

Montero hit .224 with 10 homers and 37 RBIs for the D-backs in 84 games last season, and he was 7-for-20 (.350) with seven RBIs and three home runs as a pinch-hitter, tying the franchise record for pinch-hit home runs shared by Tony Clark ('05 and '07), Greg Colbrunn ('01) and Alex Cintron ('05).

In other health news, left-handed specialist Doug Slaten threw the equivalent of two innings in a Minor League game in Tucson, Ariz. He threw 23 pitches and did very well, according to Melvin.

"Potentially, depending on how he comes through it, maybe the next time out could be in a game," Melvin said. "I would say there's an excellent chance [he'll start the season with us]. If his next time out he's able to get in a game, there should be a good chance."

The other primary question regarding the 25-man roster is Randy Johnson's readiness to join the rotation after working his way back from back surgery. Johnson threw on flat ground on Wednesday and is on track for his third Cactus League start on Friday in Tucson against the Dodgers.

"It just depends on how we get there and whether or not we feel like he can plug in there sooner than later," Melvin said of the prognosis for Johnson being in the rotation to start the season. "We'll consider all the variables, but with him, we'll err on the side of caution. The last week of spring we'll see where we're at."