When all was said and done, first-year coach Tim DeRuyter made well on that promise he made in his debut press conference in December when he declared his plan to “build a championship football team.”

After an offseason of scheme switching on offense and defense­ — and one year removed from going 4-9 and being bowl ineligible — the Fresno State Bulldogs were able to achieve a goal that has eluded them for the past 13 years.

Fresno State clinched a share of the Mountain West Conference championship in a 48-15 rout against Air Force Saturday at Bulldog Stadium­ — its first conference title since capturing a piece of the Western Athletic Conference crown in 1999.

“I’m really happy for our guys and our staff,” DeRuyter said. “All the hard work that they’ve put in, to see it come to fruition and to get a championship is a nice feeling.

“We needed a football program that competes for championships. From Day One that’s been our focus. As I’ve been out in the community, people have been starving for it. It’s been too long.”

Derek Carr completed 28 of 32 passes for 452 yards and four touchdowns and Robbie Rouse rushed for 106 yards on 25 carries in a game that helped Fresno State finish undefeated at home for the first time since 2000.

Rouse also scored his first career passing touchdown at home, where the Bulldogs have averaged almost 49 points per game this season.

“The season’s not over,” said Carr, whose team is eligible for a bowl game. “But I’m definitely going to enjoy my (championship) ring.”

The Bulldogs scored two touchdowns in their first four plays to start the game. Carr completed a 64-yard touchdown pass to Davante Adams on the team’s second play from scrimmage. It was preceded by a 28-yard reverse pass from Carr to Greg Watson to Carr to Isaiah Burse.

Fresno State would reach the end zone one minute, 46 seconds later on a 36-yard touchdown pass from Carr to Burse.

Burse hauled in a game-high 158 receiving yards and a touchdown on seven catches.

Air Force, which had not attempted a single pass during last week’s 21-7 win against Hawaii, was not able to match the Bulldogs’ up-tempo spread offense with its signature option attack.

Air Force running back Cody Getz ran for a team-high 82 yards on 19 carries.

Safety Phillip Thomas, a finalist for the Jim Thorpe Award that honors the nation’s top defensive back, was among the 22 seniors that played to play their final game at Bulldog Stadium.

“I’m going to miss the fan support,” Thomas said, after playing before a season-high home crowd of 36,240. “I’m going to miss the relationships I’ve built around the Fresno community and my teammates. I’m going to always come back and show support for my Bulldogs.

“Whether I win the Thorpe or not, you can’t take this trophy away from me.”

The Bulldogs defense — after forcing only nine turnovers in the 2011 season— created three turnovers to increase Fresno State’s takeaway count to 33, more than triple its production from the previous year.

Travis Brown, a four-year starter, led the team with 12 tackles.

Heading into halftime, Fresno State held a commanding 31-7 lead over the Falcons that was capped by a one-yard pass from Carr to Marcel Jensen in the waning minutes of the first half.

And while the Bulldogs were waiting in anticipation of hoisting the conference crown during the second half of a blowout win against their head coach’s alma mater, San Diego State was in the process of trying to fend off a Wyoming team trying to play spoiler to the Aztecs’ conference championship hopes.

San Diego State (9-3, 7-1) managed to survive against Wyoming, 42-28. The win split the conference title between the Aztecs and the Bulldogs. Boise State (9-2, 6-1) will try to make it a three-way tie for first place on Saturday when it plays Nevada on the road.

After the game, Carr announced his plans to remain at Fresno State for a final year rather than opting to leave early for the NFL Draft.

“I know we have guys who can step up who are behind Derek right now, but just knowing the type of season we’ve had that we can have another one,” said Adams, the Mountain West leader in receiving yards.

Fresno State has yet to find out which Mountain West-affiliated bowl game it will be invited to participate in this postseason.