STANFORD -- Stanford junior Usua Amanam didn't mind doing the hitting instead of getting hit. Nor did the prospect of running backward instead of forward give him pause as he pondered a switch from offense to defense after the 2010 season.
The issue for Amanam, rather, was quantifying success. As a tailback, he gained yards and scored touchdowns. But success in the secondary seemed more nuanced.
"The biggest transition for me was understanding that I could be doing well and I may not know it,'' Amanam explained.
The former Bellarmine College Prep-San Jose star found a way around that problem last week in Stanford's season-opening 20-17 victory over San Jose State. As the starting nickel back, he produced four tackles for loss, two sacks and a fumble recovery.
In his first extensive action on defense, Amanam was arguably the best player on a unit expected to be one of the stingiest in the Pac-12.
"He had never played in that capacity, and he played great," Cardinal coach David Shaw said. "Two things have never changed since he was in high school: He's quick and he's tough."
Amanam, who is of Nigerian decent -- his last name means "job well done" -- was named the Mercury News' Santa Clara County player of the year as a senior at Bellarmine, when he rushed for 1,828 yards and 30 touchdowns.
But that's not all he did.
"Most people remember Usua as an outstanding ball carrier, and he was," Bellarmine coach Mike Janda
"He made many plays for us as a free safety. He had the ability to get to the ball and diagnose plays. ... He was a force in the secondary."
Amanam considered himself a tailback and wasted little time showing his skills with the ball in his hands. As a redshirt freshman in 2010, he had a 20-yard run in the first game and caught a touchdown pass in his third.
But the Cardinal was loaded with quality tailbacks -- current starter Stepfan Taylor was only a sophomore -- and Amanam's opportunities were few.
"It's every high school running back's dream to play running back in college," he said. "But my first year, it was competitive, and I didn't get as many looks as I thought I would. When they offered me the opportunity to play defense (at the end of the 2010 season), I jumped at it.
"I played running back my entire life and thought that would make the switch to any other position easy, because it's just football. But what you do in the secondary is different."
With help from Stanford's veteran defensive backs, Amanam began to understand the techniques and concepts late last season. He showed up for spring practice confident and comfortable, especially when turned loose to blitz from the nickel position.
In training camp, he was even better, using his quickness to elude potential blockers and his experience on offense to confound them.
Having been a running back, he knows what confuses them -- as San Jose State's De'Leon Eskridge discovered after Amanam zipped past on his way to the quarterback.
"A sack's pretty fun," Amanam said. "A touchdown is one thing. But there's nothing like getting a sack."