Actually, the first day is for players to let the team know they're in town by showing up and dropping off their belongings in the clubhouse.
The real work starts on Saturday with the first official workout, which typically features a lot of stretching, a little bullpen work, and quite a bit of repetitive PFP -- pitchers' fielding practice.
It'll also be manager Bob Geren's first day at the helm of a big-league club, and while the team he inherits has changed considerably since winning the American League West in 2006 and reaching the AL Championship Series for the first time since 1992, Geren plans to change very little about Oakland's approach.
"I don't know why I would," Geren said. "This is an extremely well-run organization from top to bottom, and it has been for a long time. The A's have been a winning team year after year after year. So I'm just trying to keep a good thing going.
"Like they say, 'If it ain't broke, don't fix it.'"
Along those lines, the camp's logistics -- who goes where, and when -- will again be handled by longtime assistant coach Brad Fischer, who enters his 29th year as a member of the organization. Fischer, Oakland's bullpen coach last season, is one of just two members of the 2006 coaching staff returning to the same role.
Pitching coach Curt Young returns for his fourth season, but Rene Lachemann moves from first base to third, replacing Ron Washington, who was hired as the Rangers' new manager over the winter.
With Geren promoted from bench coach, the new right-hand man is Bob Schaefer, who has nine years of big-league experience as a bench coach and spent last season working in the Braves' front office. Ty Van Burkleo is replacing Gerald Perry as the hitting coach, having spent the previous six seasons as a roving hitting instructor in the Angels' farm system, and Tye Waller, who was the Padres' first base coach in 2006, will be in the same role this year with the A's this season.
"It's a great staff," Geren said. "We've got some new faces, so there'll be a little feeling-out period as they get to know the players and the players get to know them. But we've got a great group of coaches and a great group of guys, so I would expect they'll mesh well."
The newest face of note who will be working out Saturday is free-agent signee Mike Piazza. Though he was brought in to replace departed designated hitter Frank Thomas, he's been a catcher for all of his 15 years in the big leagues and will be among the backstops working with a slightly revamped pitching staff.
Gone is veteran ace Barry Zito, who signed with the Giants as a free agent, and expected to assume his role as the club's top starter is Rich Harden, who missed most of 2006 with injuries but made a start in the ALCS and is said to be 100 percent for Opening Day.
The other returning starters are righties Dan Haren, Esteban Loaiza and Joe Blanton, while lefty Joe Kennedy is the frontrunner to land the opening created by Zito's departure. The bullpen returns closer Huston Street and primary setup man Justin Duchscherer, and late relievers Kiko Calero and Chad Gaudin are back as well. The new guy in the 'pen is lefty Alan Embree, signed as a free agent to fill Kennedy's 2006 role.
Assuming the A's carry 12 pitchers to start the season, and Geren is leaning that way based on the early-season schedule, two bullpen jobs will be determined at camp.
Veteran righty Jay Witasick, who missed most of last season with ankle injuries, and lefty Brad Halsey appear to have the upper hand in that competition, but prospects Marcus McBeth, Santiago Casilla, Jason Windsor and Shane Komine have a shot at forcing their way into the picture, as does Rule 5 draftee Jay Marshall, among others.
Mychael Urban is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.