“They’re not rebuilding, they’re reloading.” This popular catchphrase has never been more true than it has been about Nick Saban’s Alabama.

For example, last year was one of the first instances we’ve seen in which the Tide didn’t reload at inside-backer with a new All-SEC player, largely because Shaun Dion Hamilton suffered an injury. Even still, they produced one of their finest defenses yet.

When Saban said 2018’s “biggest concern no one is talking about is our secondary,” it was hard for many people to take him seriously.

Saban can probably find a concern or five with any of his previous teams that won championships. When Saban is discussing his problems, he typically sounds like the boy who cried wolf, more like he’s trying to keep his team insulated from press clippings than giving an honest appraisal.

In 2018, though, the Tide really are facing a uniquely comprehensive rebuild in the secondary.

1. They’re once again overhauling their defensive backs coaches.

This is probably the least intimidating challenge, considering Saban’s personal expertise at coaching DBs.

Jeremy Pruitt became the latest Saban defensive assistant with secondary coaching on his resume to take a head coaching job, but he focused on linebackers over the last two years. The man in charge of the secondary over the last two years was Derrick Ansley, coaching DBs for the Oakland Raiders now.

Saban brought Karl Scott from Texas Tech to man the post for 2018, but everyone knows Alabama’s head man is very hands-on with the DBs himself. No matter who coached the 2018 secondary, there was little question over whether Saban would mostly delegate the responsibility or choose that spot to be particularly involved.

2018 will feature a new DB coach and a new DC, but ultimately, it’ll be Saban’s vision, and he’s proved quite capable of coaching coaches to execute it.

2. There’s no lockdown corner returning.

There’s been only one year since 2008 in which Alabama started without at least one returning starter at cornerback. That was 2010, in which they only returned a single starter from their nickel package (safety Mark Barron) and had guys in their third years or younger at every spot.

They did just fine, finishing No. 8 in passing S&P+ on the year and No. 1 on passing downs. A key was their ability to plug in a former five-star at one spot in sophomore Dre Kirkpatrick and a former five-star at the other in freshman Dee Milliner. They combined to break up 15 passes and intercept three while setting up safeties Barron and Robert Lester to wreak havoc, picking off 11 passes while hawking from deeper alignments on the passes opponents tried to force past the tight corner coverage.

The 2018 corner positions are still shaking out, but likely being manned by junior Trevon Diggs (a former four-star) and JUCO transfer Saivion Smith (a former four-star), who was able to take part in spring practices.

It’s possible that Diggs and Smith will prove to be stars who just needed their chances to shine, but there’s a lot less certainty at corner than Alabama has had in almost a decade, and there’s some question as to whether the Tide were stuck going young in 2010 or if they were pushed to do so by the undeniable Kirkpatrick and Milliner. They became first-rounders, and we can’t just assume 2018’s new guys will reach that level.

Similarly, the 2013 secondary had some weak spots that were rarely exposed, save for when they faced Johnny Manziel and Mike Evans in College Station.

The key problem was a lack of a big corner who could hold up down the sidelines without help, to allow Saban’s anti-spread coverages to thrive. On this play, the Tide brought a five-man pressure and left both corners in press-bail coverage down the sidelines and couldn’t stay over the top.

The 2017 Tide were defined more by their ability to lock down against inside receivers with nickel and dime sub packages (read, Minkah Fitzpatrick) than their corner play, but Levi Wallace was an All-SEC selection and Anthony Averett was a multi-year starter who went in the middle of the NFL draft. So the Tide weren’t exactly weak at cornerback.

3. These safeties and nickels are green.

It’s not uncommon for young cornerbacks to thrive early in their careers. If you’re a great athlete with good technique in man coverage, then even Saban’s complex playbook of pattern-matching coverages can become fairly simple, since the CB often ends up in man coverage anyway.

The safety positions, though? Their roles have complex reads and assignments in those pattern-matching coverages, and it’s common for talented safeties to need a few years to learn how to play fast, yet mistake-free. It also takes time to learn film study and gain the knowledge of how to attack opponents’ tendencies while living up to their role as the last line of defense.

Alabama is replacing its starting safeties and nickel, plus the dime. This is the first time they’re replacing all three main interior DB positions since 2014, and that season wasn’t up to standards. They finished 17th in passing S&P+ and 32nd on passing downs that year and were badly burned by Ohio State’s run/pass balance in the Playoff.

The Tide replace Fitzpatrick, one of Saban’s best DBs ever, but also Laurence “Hootie” Jones, Ronnie Harrison, and Tony Brown. Harrison and Fitzpatrick were the Tide’s leading solo tacklers, shoring things up as Bama rotated linebackers amid injury, with Jones and the corners close behind.

Deionte Thompson, a former four-star, started both Playoff games when Jones was out with injury. He was solid, if unspectacular. Former four-star Xavier McKinney figures to start alongside him as a true sophomore, and his experience is mostly limited to special teams and mop-up snaps. At the nickel will likely be junior Shyheim Carter, another former four-star, who’s likewise lightly experienced.

One hope for these safeties is that Alabama has a particularly heady group that will take to Saban and Scott’s teaching quickly and be ready to go against Bobby Petrino’s reworked offense in week one. The other is that the green outside guys will prove highly skilled in coverage and tee up the safeties for easier assignments, more like 2010 than 2014.

For the Tide to play to their normal standard, they need as many as six unproven players to pan out at the same time.

The 2017 secondary had four returning starters on the field in its dime package, combined with two seniors. This unit won't have a single senior (although Thompson will be a redshirt junior) in addition to lacking a single returning starter.

Which of these guys will be able to walk his teammates through the plan on Saturdays, when they’re on the field together? How well will this unit hold up against some of the veteran QBs coming back this season in the SEC?

It’ll probably all work okay, at least to the tune of another double-digit-win season, but this is unchartered territory for Saban’s perpetually reloading Alabama, and it’s a reason for non-Bama fans to pay a little more attention to the Tide than usual.