He is the coach who could have been.

Mike Riley is the longest tenured coach in the Pac-12, and Oregon State is thrilled about that. But he might have spent all those years at USC if fate hadn't swerved, like a flashy tailback in the open field, at the last minute.

It was late in 2000, and Riley was coaching the San Diego Chargers at the time, suffering through a difficult season. Trojans athletic director Mike Garrett, remembering how respected Riley was as a former USC offensive coordinator, had picked him as his guy after an impressive interview.

Before USC hired Pete Carroll in 2000, Mike Riley was a top candidate for the Trojans job. AP Photo/Eugene Tanner

All that was left was President Steven Sample's approval, and Riley was in a limo on the 405 freeway, coming to Los Angeles to seal the deal when his cell phone rang. It was Chargers president Dean Spanos telling him if he made the trip to L.A. for the interview he no longer had a job in San Diego.

"I had a family and I just couldn't take the risk," Riley explained. So he eventually went to Oregon State, while USC's frantic search for a new head coach still turned out OK.

Pete Carroll was hired a few weeks later.

While Carroll and the Trojans flourished, Riley and the Beavers managed to more than just persevere.

Think what he has accomplished in tiny Corvallis. No coach in America has done more with such limited resources. Let's just say that not many five-star recruits rush to put Oregon State on their wish list.

"What you have to do here is uncover rocks," a smiling Riley once told me.

Some of those rocks have felt more like boulders to USC.

In 2006, Riley knocked off an undefeated, No. 3-ranked USC team, 33-31, costing Carroll a shot at a national championship. Two years later, it was even worse. Carroll came to Corvallis ranked No. 1 in the country after an overwhelming 35-3 victory over Ohio State. It was a Trojans team that featured Clay Matthews Jr., Rey Maualuga and Brian Cushing -- the best defense of the Carroll era.

It didn't faze Riley. The oddsmakers made Oregon State a 25-point underdog in the nationally-televised Thursday night match up. A USC team suffering an obvious emotional letdown from the Ohio State game came out flat, and Riley kept giving the ball to little Jacquizz Rodgers, who spent the entire night snaking his way through that vaunted Trojans' defense.

Oregon State raced out to a 21-0 lead and held off a mild Mark Sanchez rally to win the game, 27-21. Carroll admitted later it was one of the two toughest losses during his time at USC. That Trojans team, arguably the best one Carroll coached, finished 12-1, winning the Rose Bowl. But because of that loss in Corvallis, it never got a shot at the BCS title.

What makes Riley so unique isn't just his coaching skill. It is his demeanor. In all the years I've been around sports, he is the nicest, most unassuming coach I've ever covered -- at any level. He reminds you more of a friendly neighbor than a guy who competes in one of the most intense conferences in the country.

"If you get to heaven and Mike Riley's not there," said former USC coach John Robinson, "then you've gone to the wrong place."

The more you watch Riley's football teams, the more you can't help but wonder what he could do with a truly bigtime program. We came very close to finding out.

Not only did he just miss out at USC, he was a finalist for the Stanford job that eventually went to Buddy Tevens. A former defensive back for Bear Bryant at Alabama, he was a candidate there, too. He might have had that job if UCLA hadn't come calling.

"I turned down Alabama waiting for UCLA," Riley said. When the Bruins' job went to Karl Dorrell, Riley says he felt "like I'd been kicked in the stomach." At that point, Riley was more than discouraged. "I don't want to sound too dramatic about lost faith and all that, but I have to admit to thinking, ‘Whoa, what's going on here?'"

Eventually, everything turned out fine, though. Riley grew up in Oregon, played at Corvallis High, and returning home to coach proved to be a happy decision for him and his family.

Saturday night, in yet another pivotal game for USC, Riley will trot out of the Coliseum tunnel and stand on the opposite sideline from Steve Sarkisian.

As coaching match ups go, take it from Carroll. Sark should expect to have his hands full.