We continue our series looking at the positions of strength and need in the Pac-12. Next up is Stanford.

Positions of strength: Running back and secondary

Key players: RB Christian McCaffrey, RB Bryce Love, CB Alijah Holder, CB Quenton Meeks

After blowing away the FBS single-season all-purpose yardage record, what will Christian McCaffrey do for an encore? Kyle Terada/USA TODAY Sports

How this unit is shaping up heading into 2016: I had to break the rules and list two positions here, because ... McCaffrey. The Cardinal's secondary -- so young and vulnerable entering last season -- grew up over the course of 2015. That defensive backfield will be a force to be reckoned with moving forward, and I'll write about them in more detail in the next paragraph, but let's establish this first: Any Stanford "position of strength" discussion that fails to mention McCaffrey and Love at running back is downright irresponsible.

With that being said, how about that Cardinal secondary during the final two games of last season? The unit endured extreme growing pains against the likes of Oregon and Notre Dame -- particularly without senior leader Ronnie Harris. His return from injury for half of the Pac-12 championship game and the entire Rose Bowl gave Stanford a massive boost.

The Cardinal must move forward without Harris, but his impact will continue to be felt moving forward: He shepherded a young batch of improving talent featuring Holder, Meeks and Terrence Alexander into lockdown mode by the time Jan. 1 rolled around. Meeks' pick-six in the Rose Bowl and a flurry of "coverage sacks" in that game might have been a taste of the Stanford secondary's future.

Position of need: Defensive line

Key players: Solomon Thomas, Harrison Phillips, Luke Kaumatule, Eric Cotton

How this unit is shaping up heading into 2016: This position group was in a precarious situation entering last season, when it had to replace all three of its 2014 starters. Aziz Shittu and Brennan Scarlett -- Stanford's first-ever graduate transfer -- both delivered big years to soften the blow up front. With those two seniors gone, the Cardinal must move to the next contingency plan along the defensive line.

Physical freak Solomon Thomas, who shined in his first season of play, is projected to be the stalwart of the group. Stanford also has high hopes for Phillips, who'll be returning from a season-ending knee injury suffered early in last year's opener. Beyond those two, it's a projected free-for-all that's integral to the Cardinal's fortunes. The coaching staff took the unusual move of redshirting Kaumatule during his senior season, and they hope that the 6-foot-7, 280-pounder can finally settle into a defensive end role after four position changes in four years. There's also hope that Cotton can contribute after a position switch from tight end. Dylan Jackson impressed in practice during his redshirt year.

All in all, this defensive line group is filled with wild cards, but Stanford badly needs to build depth with the pieces that they have. New position coach Diron Reynolds, successor to the retired Randy Hart, will immediately have his hands full.