TUCSON (AP) - The Arizona Diamondbacks established stability on the field last autumn, winning the NL West title with a mostly homegrown roster.

Now the Diamondbacks believe they've taken a step toward stability in the front office, giving eight-year contract extensions to general manager Josh Byrnes and president Derrick Hall on Thursday. The deals, which expire in 2015, were announced as the NL West champions held their first full-squad workout on a cool, sunny morning. Terms were not released.

``We couldn't be prouder of the work that they've done for us,'' general partner Jeff Moorad said. ``We're looking forward very much to the work that they'll do in the future over the next eight seasons.

``I'm already worried about 2016,'' Moorad said with a chuckle.

The Diamondbacks have been searching for consistency since a new ownership group took over in August 2004, signaling the departure of Jerry Colangelo, who headed the group that brought major league baseball to Arizona in 1998.

One month after the new owners came in, the Diamondbacks ended a 111-loss season. Then the club endured a public-relations fiasco when it hired manager Wally Backman, only to dismiss him a few days later amid questions about his background.

``When our group came aboard at the end of '04, we were in a pretty difficult place,'' managing general partner Ken Kendrick said. ``And we tried to assess where we were and what we wanted to do. It's been a slow process to get the right mix of front office people, the right leadership on the field and the right players. You don't do that overnight.

``Now we think we have all those things in place,'' Kendrick said. ``We'll see if we've made the right choices. We think we have.''

The extensions for Hall and Byrnes come a few months after the team extended reigning NL Manager of the Year Bob Melvin's contract through 2010.

The 37-year-old Byrnes, who became general manager in October 2005, helped construct the young but talented team that won the NL West last year and advanced to the NL championship series despite a payroll of $70 million that was 23rd among the 30 major league clubs.

Byrnes said he appreciates working for an ownership group that is involved but allows him autonomy.

``It's a great work environment, from ownership through my office on down,'' said Byrnes, who worked under Boston general manager Theo Epstein. ``I really feel privileged to be part of this organization. It's unique.''

Byrnes succeeded Joe Garagiola Jr., the team's only other general manager. Garagiola resigned in 2005 to join the commissioner's office as senior vice president of baseball operations.

Garagiola left a thriving minor league system that produced Cy Young Award winner Brandon Webb, shortstop Stephen Drew and right fielder Justin Upton, all considered cornerstones of the future. (Upton was drafted during Garagiola's regime but signed by Byrnes).

Byrnes added to the mix by acquiring Orlando Hudson, who made the All-Star team and won his third Gold Glove last year, along with center fielder Chris Young and lefty Doug Davis. He also signed left fielder Eric Byrnes.

``He's done a superior job from day one,'' Kendrick said. ``We've had on-field success. He's built a great staff. We've had on-field success. We have a very, very strong minor league system, and certainly some of that was inherited.''

The 39-year-old Hall has been president since September 2006. Owners cited his efforts to rebuild a fan base that eroded in the years following the team's 2001 World Series title.

The club's attendance has been a concern for years; after drawing 3.6 million fans in its inaugural season, Arizona's attendance dropped in six of the next seven seasons.

Last year, attendance climbed for the second year in a row, to 2.3 million. Hall said season ticket sales are up this winter, and he believes the club can draw 3 million per year as fans in a rapidly growing market identify with a homegrown roster.

``I think our fans see that this team is for real,'' Hall said.