It put an explosive finishing touch on one of Stanford’s best defensive performances in recent memory. It marked the start of a season that would nearly double the number of turnovers that went in Stanford’s favor. It demonstrated definitively that the Cardinal secondary would be a force to be reckoned with.

And it almost didn’t happen.

After the Cardinal went up 21-0 against UCLA in the waning moments of the third quarter last September, junior free safety Michael Thomas wasn’t ready when Bruin quarterback Kevin Prince took the field.

“It was the first play of the series, so honestly, I wasn’t even strapped up and ready to play,” Thomas remembered. “As soon as the play happened, I was running out and just trying to get a hit on the quarterback even though I wasn’t strapped up…I realized the quarterback had the ball and the defensive linemen were coming up to tackle him. He wasn’t turning his feet, and he was giving up ground.”

Thomas thought back to the work the secondary had done with new defensive backs coach Derek Mason in training camp. When Prince bobbled the snap, Thomas — already having forced a fumble on the night — didn’t give him any time to regroup.

“That was something we had been practicing all camp long, getting strip attempts on offensive players when they weren’t paying attention, and I saw an opportunity right there,” he said. “We had just talked about it that week. The first thing that was going through my mind when I stripped the ball was, ‘Please do not get caught.’”

Twenty-one yards later he was in the end zone, putting a dramatic flair on a 35-0 shutout win in Pasadena that included two interceptions and two fumble recoveries for Stanford. The Cardinal would go on to force 30 turnovers last season, jumping to 12th in Division I after ranking 99th in the category with 17 in 2009. The secondary alone forced seven fumbles, up from three the year before. And with three of four starting defensive backs returning this season, things are looking up for a secondary that is possibly Stanford’s most experienced unit on the field.

Just as with the front seven, the Cardinal’s revitalization in the secondary was sparked in part by a new member of the coaching staff.

“When Derek Mason took on the secondary, he basically restarted from ground zero in terms of the basics of defense and how to play the position of defensive back,” Thomas said. “Instead of in 2009, when it was [cornerback Richard] Sherman’s first year playing defense, it was [strong safety] Delano Howell’s first year starting, and I wasn’t even in a starting role yet…the chemistry was just there. It showed out on the field the way we play together.”

It certainly did, with Stanford’s pass defense improving by over 60 yards per game and forcing more interceptions (18) than any Cardinal team in the last 15 years. Rising seniors Thomas, Howell and cornerback Johnson Bademosi have gotten used to playing together in their combined 47 career starts.

“The great thing about our team is that we mesh really well,” Howell said. “We’ve got good relationships on and off the field, so we have confidence when we get on the field. Our leadership is something that we have confidence in, and I feel like we’re going to take advantage of our situation. In game situations, having a composed and mature group is important.”

The secondary does lose its most experienced player on paper, Sherman, who made 37 starts over five years. But over half of his time on the Farm was spent on the offensive side of the ball, before the flashy receiver made the transition to cornerback leading up to his redshirt junior season.

“Shoot, Sherman was just an athlete,” Howell said. “When you gave him the football, he just knew how to play ball, whether you put him on offense or defense. It’s kind of amazing how quickly he was able to transition without having played the position before.”

“He was phenomenal in his confidence and his willingness to learn. I mean, you don’t really see that too much in many athletes, especially at this level, but he did something that’s really hard to do,” Howell added.

Sherman was hardly the only Stanford player to move to secondary from the offensive side of the ball over the past few seasons. Howell himself made the switch after playing running back his freshman year; Thomas, recruited as a speedy quarterback out of high school, became a safety during his first training camp.

And the Cardinal was at it again this spring, converting another talented player out of the backfield into a defensive back. With all five members of Stanford’s generally young running-back tandem returning, Usua Amanam was switched to cornerback after playing in 11 games as a redshirt freshman in 2010.

Thomas speaks highly of his teammates that have played on both sides of the ball at the college level.

“Those guys are like animals,” he said of Howell and Amanam. “It’s kind of natural for them. It’s the same foundation you go through, out there trying to make somebody miss.”

But while Sherman and Howell were thrust into starting roles immediately due to deep holes in the secondary, the coaching staff likely converted Amanam in anticipation of the departure of all three senior defensive backs following this season. He may see light action this year at right cornerback behind Bademosi.

Instead, the open left cornerback spot is expected to be filled by rising sophomore Barry Browning, who saw action in all 13 games last season.

“He is athletically incredible, but [we’re also impressed by] his attitude, his confidence and his willingness to constantly get better,” Howell said. “He’s got high expectations for himself, and the thing about him is that he’s very good at keeping a level head. He realizes that there’s a lot of growth that’s needed in terms of where he wants to go.”

“He’s faster than anyone I’ve played with in a long time, other than [senior wide receiver] Chris Owusu,” Thomas remarked.

Despite the Cardinal’s experience in the secondary, the defensive backs will have their fair share of tough tests in the year to come. Five Pac-12 quarterbacks were named to the Davey O’Brien watch list for the best passer in the country earlier this summer, and Stanford will face three of them: Oregon’s Darron Thomas, USC’s Matt Barkley and Arizona’s Nick Foles. All three passers threw over 230 yards against the Cardinal last year, with Barkley going for 390 in a close Stanford win.

Adjustments need to be made on a week-by-week basis due to these quarterbacks’ varied styles.

“It’s cliche, but we take everything one game at a time,” Thomas said. “Each quarterback is different. You get Darron Thomas, he’s going to be a running quarterback…it’s a full-team effort, everyone is putting their all into it, just trying to make sure we do our job to stop them.”

This is part two of a four-part series previewing the 2011 Stanford football team. Stay tuned next week, as we take a closer look at the Cardinal running game.

Part One: Front Seven (July 28)