"Everything's gone really well with therapy," Ellis told MLB.com by phone from his offseason home in the Phoenix area. "But four months is a long time to go without doing anything, so it's going to take some time to get my arm strength back. What's nice is that Spring Training is a little longer this year.
"If I can get 30, 35 at-bats before the season starts, that should be enough to be ready for Opening Day."
Ellis, 31, suggested that those at-bats will come in the final two weeks of Spring Training, preferably against big league pitching. Most teams use the final two weeks of Cactus League action to get their starters stretched out to six or seven innings, after which they typically use only relievers projected to make the 25-man roster
But with their Minor League facility just up the road from Phoenix Municipal Stadium, the A's often send players in need of extra late-spring action to play in Double-A and Triple-A games.
"That's the great thing about Spring Training," Ellis said. "You can get as much work in as you want. There's a lot of different ways to do it."
"We're obviously not going to rush him," A's manager Bob Geren said. "The idea is to make sure he's ready for Opening Day, and from everything I've heard, everyone's pretty confident he's going to be ready when we need him."
While Ellis is working his way back into game shape, Geren plans to give several players an opportunity to play this spring.
"We've got a lot of guys who'll be in there," said Geren, who mentioned Eric Patterson and Cliff Pennington by name. "It's not going to one guy getting all the at-bats."
Also invited to camp is Jemile Weeks, a second baseman whom the A's selected in the first round of last June's First-Year Player Draft. Weeks suffered a season-ending hip injury shortly after signing with Oakland last summer, but he's expected to be ready to play right away this spring.
Ellis said he'll start throwing Monday, marking four months to the day since the Sept. 19 surgery. The following Monday, he'll start hitting.
"I saw the doctor yesterday and he was happy with everything, so I'm good to go," Ellis said Wednesday. "I'm excited to get back out there; therapy was pretty boring."
The surgery, performed by Dr. Freedberg and A's orthopedist Dr. John Frazier, repaired Ellis' labrum, which he tore in a Spring Training collision with Bobby Crosby in 2003.
Ellis opted for rehab over surgery and missed the entire 2004 season, but he came back the following year with the best of his six seasons in the Majors, leading the team in batting (.316), slugging percentage (.477), on-base percentage (.384) and triples (five) while providing his usual Gold Glove-caliber defense.
Although Ellis' offensive numbers fluctuated for the next two seasons -- he batted .249 in 2006 but established career highs of 19 homers and 76 RBIs in 2007 -- his defense certainly never suffered. In 2006 he set what was at the time the all-time record for fielding percentage (.997) by a second baseman, and in 2007 his .994 fielding percentage was second-best in the American League.
In 2008, Ellis again led the AL in fielding percentage (.993) but was batting a career-low .233 when the shoulder forced him to miss the final month of the season.
"It started bothering me a little in June," Ellis said. "I don't remember what [triggered it] exactly; I think I just kind of banged it up a little. But it went away for a while and then came back a little bit [in August] and then it just got so bad we had to shut it down."
Eligible for free agency this winter, Ellis decided against entertaining outside offers and re-signed with Oakland for two years and $11 million, with a club option for 2011, in October.
Asked if a specific schedule or timeline has been set for his return, Ellis hedged.
"I don't really want to put a date on it because I don't want to be disappointed if I don't make it back by then," Ellis said. "It all depends on how quickly I get my arm strength back, and last time it took a really long time. And since I've been through this before, we're just going to be really patient with it."