OAKLAND -- Marco Scutaro, Nick Swisher and Mark Kotsay now wear different uniforms, Eric Chavez and a host of other A's are on the mend, and the rest of the club's position players are either new to the team or largely unproven.

So when second baseman Mark Ellis reports to Spring Training in Phoenix next month, he'll do so as the only Oakland position player who qualifies as a "Sure Thing."

And for the presence of Ellis, who posted career highs in nine offensive categories, while again providing near-flawless defensive work, second-year manager Bob Geren is most thankful.

"Mark is a 100-percent intelligent baseball player," Geren said on Tuesday. "He understands the game, he understands the league, he understands his position on the team. He's basically one of the smartest players you'll ever meet.

"He's capable of anything."

With that in mind, Geren is certain that Ellis, 30, won't even need to be told that in addition to being counted on to continue playing the game as well as any second baseman in A's history, he'll be counted on to play a significant leadership role on a team that will, at many positions, be as green as the lettering on Oakland's home whites.

"Oh, there's no question he'll be a team leader," Geren said. "Whether you're a first-year player or a veteran, you can't help but look at Mark's work ethic and the way he goes about his business and admire it. He's perfect for being on a young team."

On the other side of second base for the A's this year will again be the unfortunate soul whose recent injury history has turned him into anything but a Sure Thing in the minds of many A's fans.

Shortstop Bobby Crosby, the 2004 American League Rookie of the Year, has made five trips to the disabled list over the past three seasons, limiting him to fewer than 100 games each year, and he bottomed out in 2007 by batting .226 with eight homers, 31 RBIs and a .278 on-base percentage -- all career lows -- before missing the final 62 games with a broken bone in his left hand.

As a result, Crosby, who turned 27 earlier this month, has been the target of some vicious criticism on blogs and Web message boards. Among the printable labels with which he's been affixed are "bust," "fragile" and "useless."

Oakland Athletics • Catchers: Suzuki set for first full year • Corner IF: Barton ready to make mark • Middle IF: Health is key for combo • Outfielders: A's will be athletic • Starters: Blanton takes over as ace • Bullpen: Street holds key to 'pen • DH/Bench: Cust leads the pack

Crosby's teammates, however, virtually jump to his defense, calling the criticism unfair at best. And Ellis is at the front of the line.

"I don't think it's fair at all," Ellis sternly offered when the topic surfaced in September. "He's out right now with a broken hand because he got hit by a 98-mph fastball. He's been on the DL with a broken ankle [2005] after a collision at home plate. He's been on the DL after getting drilled in the ribs [2005]. He's missed time after getting spiked at the bag [2006]. That kind of stuff happens in this game. It's not like he's sitting out with something you can't see on an X-ray or with your own eyes. It's not like he's dogging it in rehab.

"He's just been super unlucky. Sooner or later, his luck's going to turn and he's going to be the player that everyone in this room knows he can be."

When it was pointed out to Geren that Crosby wasn't particularly good when he was healthy last season, he bristled.

"For one thing, he missed out on most of last offseason because of back problems that cost him time in Spring Training, and that impacts you for longer than some people might realize," Geren explained. "I don't think anybody in the organization is down on Bobby at all, because we know he's had some freak injuries over the past few years, and we know how hard that can be on a guy's development. You get hurt, you come back, you start to feel like you're getting back on track, and then you get hurt again and have to start all over again.

"That's what it's been like for Bobby since his rookie year. He gets off track, he gets on track, he gets knocked off again. When you miss time with injuries and you're always coming back, you're going to struggle to find your way until you can get an entire healthy offseason, a full Spring Training and a healthy season all put together, one after another. That's all Bobby needs. I truly believe that."

So does Crosby, who worked hard toward a return to the field at the end of the 2007 season but, with the team hopelessly out of playoff contention, was eventually told to shut it down and focus on the offseason.

The worst part of the hand injury, Crosby said, was that it came at the end of a game in which he felt as good at the plate as he'd felt all year. He was 2-for-2 with a walk on July 24 in Anaheim when an eighth-inning heater from Justin Speier broke his hand in two places.

"To go through what I did last year, then have my struggles this year, then finally feel like I've figured something out and then go down again, it's indescribable how depressing it is," Crosby said the day after being drilled. "I did all I could in the offseason and during the season trying to stay healthy. Yesterday was the first day in probably about a month and a half where I felt great at the plate and felt like I had figured something out.

"I mean, you can only do so much in order to prepare -- and then you get hit by a fastball in the hand. I don't know what to say. It's the most depressing thing ever."

As of now, though, life is good for Crosby. He got married this winter, and his offseason workouts have gone off without a hitch.

"He's ready to go," Geren said. "I'll tell you what, he's a guy I'm really pulling for. He deserves a nice run of good health here, and when he gets it, you're going to see a pretty special player."

If the injury bug bites Crosby again, or if it finds its way over to Ellis, Geren won't have Scutaro around to bail the A's out of any middle infield issues. The fan favorite was traded to the Blue Jays early in the offseason and will be replaced as the team's top utilityman by Donnie Murphy, who started 30 games at shortstop while Crosby was out but also can play a capable second base.

"Marco swung the bat well and got a lot of key hits over the past few years, so there's some offense we're missing, but I feel confident with the young guys coming up," Geren said. "Donnie Murphy can do a solid job all the way around."

As for the other young guys, they include Kevin Melillo, a second baseman who got a cup of coffee with the A's last year and batted .262 with 10 homers and 55 RBIs in 98 games with Triple-A Sacramento. Shortstop Gregorio Petit, who split last season between Double-A Midland and Sacramento, and Minor League free-agent signee Brooks Conrad also are among the prospects who will be in camp.

"This is gonna be an exciting spring as far as some guys getting some good, long looks and opportunities," Geren said. "I've talked to some of them, and the enthusiasm in their voices in infectious. Guys are going to be pumped up and have a chance in this organization, and that adds some fun to everything that's going on."