A year ago at this time, Stanford was tasked with replacing nine starters on the defensive side of the ball. There were serious questions about the unit's ability to maintain the unprecedented level of stoutness it had attained in 2012-14.

"Our youth is significant -- it's there," coach David Shaw said at the time. "But so is the talent."

Another Rose Bowl win later, it's apparent Shaw's observation was accurate. The new-look Stanford defense did suffer growing pains because of its inexperience, but it ultimately blossomed behind enough athleticism and play-making ability to complete the team by the end of the season.

Now the Cardinal defense faces yet another reloading effort, though this one looks like an inverted version of last year's.

Entering 2015, Stanford's primary spot of inexperience was the secondary.

Entering 2016, it's the front seven, while the secondary looks primed to be the core of the unit.

A young crop of defensive backs, all touted recruits, made impressive strides in 2015, culminating in true freshman Quenton Meeks' 66-yard pick-six in the Rose Bowl. The majority of that group will be back, and they'll also get a boost from versatile fifth-year man Zach Hoffpauir, who pulled a Tyler Gaffney -- he'll return to the lineup after spending a year playing professional baseball.

With Meeks, Hoffpauir, Alijah Holder, Terrence Alexander, Dallas Lloyd, Ben Edwards and Justin Reid, Stanford has reason to believe its secondary can grow into a lock-down force in 2016. The key may be replacing cornerback Ronnie Harris' leadership.

Stanford cornerback Quenton Meeks returns an interception for a touchdown in the Rose Bowl. AP Photo/Mark J. Terrill

But elsewhere, the situation is murkier. The importance of senior defensive linemen Aziz Shittu and Brennan Scarlett was undeniable in 2015, especially at season's end when Stanford's pass rush roared to life. The Cardinal recorded 23 sacks through the first 12 games (an average of 1.9 per game) before tallying 11 sacks in the final two games (5.5 per game).

If the pass rush is going to be effective, it'll have to do so without Shittu and Scarlett. That puts immense pressure on Solomon Thomas -- a budding star in 2015 -- and Harrison Phillips, who tore his ACL just a few minutes into the season. Phillips popped on tape in the short window before he went down, and he's ahead of schedule in his rehab, so defensive coordinator Lance Anderson is cautiously optimistic about his core up front.

Depth is the biggest unknown. Stanford took the unusual move of redshirting senior Luke Kaumatule in anticipation of a 2016 talent shortage on the line. He's a 6-foot-7, 278-pound specimen, but Kaumatule has never been able to establish himself at a single position -- he's moved from defensive line to tight end to defensive line to outside linebacker and finally back to defensive line. Anderson hopes that the latest move, combined with the redshirt year, will finally unlock Kaumatule's potential.

Anderson also expects contributions from Dylan Jackson and Eric Cotton -- a recently converted tight end -- along the line. The latter will be asked to pack on about 15 pounds this offseason to accommodate the position change.

At linebacker, Stanford is tasked with replacing Blake Martinez, whose 140 tackles led the Pac-12 in 2015. There's obvious concern here since coaches say Martinez masked so many of the defense's shortcomings with his gaudy stop total. Noor Davis, Kevin Palma and Jordan Perez must all make strides, while special teams standouts like Mustafa Branch are expected to enter the rotation at inside linebacker.

The Cardinal are more comfortable on the outside, despite Kevin Anderson's graduation. Speed rusher Peter Kalambayi returns, and the staff enjoyed promising development from fellow 'backers Joey Alfieri and Mike Tyler. Anderson is confident his unit can bring continued heat from the edge -- provided the interior up front holds up its end of the bargain.

At the very least, 2016 is unfolding with an interesting dynamic. Historically this program hasn't been known for its secondary play. But the tables have been turned in that regard. The Cardinal's defensive backbone may reside with their defensive backs, and that's a notable shift.