To the extent he allows himself to enjoy anything, Nick Saban must be enjoying this week as much as any in a long time. For once, he’s not even bothering to pretend otherwise: On Wednesday, he showed up to a press conference — typically stern, businesslike affairs, except on the days Saban opts to vent his frustration with the media at large — in such an uncharacteristically good mood that he saw fit to open the proceedings with a joke. (A tried-and-true, decades-old dad joke, yes, but nevertheless: Unmistakably a joke.) By Saban standards, he was almost giddy.

And why not? For the first time in what seems like a very long time, there are legitimate doubts this week about the extent of his team’s invincibility.

Alabama remains unbeaten, of course, one of only three major-conference teams that still boasts a ‘0’ in the loss column, and is still riding the wave of a 24-game conference winning streak dating to September 2015. It remains firmly entrenched at the top of both major polls and the weekly Playoff rankings. But the Crimson Tide are also coming off their most harrowing outing of the season, a 31-24 scare at Mississippi State in which they trailed in the fourth quarter for the first time all year, and which validated Saban’s repeated warnings about the danger of complacency, aka “rat poison.” According to ESPN, more people tuned in to watch the narrow escape than any other game on any cable network this year, breaking the monotony of by-the-book blowouts whose outcome was never in doubt. For many viewers, it was the first Alabama game since the season opener against Florida State that seemed worth watching at all.

In retrospect, the close call in Starkville also recast Bama’s other competitive, four-quarter games this season as the rule against quality opponents rather than the exception. Against the three best teams they’d faced prior to Mississippi State — Texas A&M, LSU, the healthy version of Florida State — the offense looked ordinary, failing to reach 28 points or 400 total yards in all three games. LSU held the Tide to one of their worst offensive rushing performances of the past five years, while also delivering the best rushing performance against Alabama’s defense since the 2014 Playoff loss to Ohio State. Mississippi State’s ground game fared even better, grinding out 172 yards, three rushing touchdowns (most by an opposing offense in the Saban era), and an 18-minute advantage in time of possession.

And while none of the above is enough to knock Bama from its perennial perch in the polls, taken as a whole it has dealt a serious blow to the aura of inevitability that surrounded the first two-thirds of the season. In Vegas, the point spread for next weekend’s winner-take-all showdown with Auburn dropped by a full touchdown overnight, from Alabama -10 to Alabama -3, reflecting both the Crimson Tide’s lackluster showing at MSU as well as the eye-opening beatdown Auburn just put on their East Division doppelgänger, Georgia. Beyond the Iron Bowl, there are significant questions (some mounting skepticism, even) about the Tide’s potential to sustain a Playoff run at the end of a season that has yet to present them with a remotely Playoff-worthy opponent. As the stakes rise, so does the uncertainty.

For a coach like Saban, who thrives in the gap between greatness and perfection — and who will not hesitate to exploit media skepticism for motivation, even if he has to invent it out of thin air — that presents an ideal scenario for keeping his team hungry and focused as the season approaches its climax. For the rest of us, it begs the question: Is Alabama, the unquestioned front runner from day one, really vulnerable down the stretch? Or are we just grasping at straws for the sake of a little drama in the absence of a viable challenger? We’ll find out soon enough. For now, after months of marveling at Bama’s routine dominance, here are five reasons the answer could be the former (really):

1. The Injury Struggle is Real. Saban’s teams, like all teams, have dealt with significant injuries before. But the string of bad luck Alabama has faced this year at linebacker, specifically, is beginning to look like a real issue. On the outside, the Crimson Tide have played virtually the entire season without a pair of edge rushers, Christian Miller and Terrell Lewis, who were both expected to take on prominent roles until they went down with biceps and elbow injuries, respectively, in the season-opening win over FSU. On the inside, they’ll be forced to play the rest of the way without sophomore Mack Wilson (foot) or senior Shaun Dion Hamilton (knee), both of whom suffered season-ending injuries against LSU. Hamilton, in particular, is a returning starter from 2016 who led the LB corps in tackles before his injury and served as one of the veteran leaders on the field who made sure everyone was on the same page.

Credit: John David Mercer-USA TODAY Sports

In Alabama’s case, the general assumption is that there will always be enough blue-chip athletes on hand to plug in without much noticeable drop off from the starters, and in the past that’s largely proven to be true. (Although the absence of All-SEC safety Eddie Jackson was certainly felt in last year’s championship loss to Clemson.) But that much attrition at one position is bound to leave any lineup thin. Hamilton’s replacements against Mississippi State, Keith Holcombe and Dylan Moses, took much of the blame for the Bulldogs’ slow but steady success running between the tackles — especially Holcombe, who offered little resistance on either of Mississippi State’s first two touchdown runs (both of them coming right up the gut) and on the third was left grasping at air in pursuit of MSU quarterback Nick Fitzgerald.

Moses, a true freshman, played sparingly off the bench in Starkville but might be in line for his first career start Saturday against Mercer; he and Holcombe are listed as co-starters at MIKE. Elsewhere, the SAM linebacker spot will be manned by a former walk-on, Jamey Mosley, who has started three games this season (against Fresno State, Colorado State, and Arkansas) but has yet to transcend his identity as C.J. Mosley’s little brother. With Hamilton out, the only remaining linebacker who would have had any chance to sniff the starting lineup on any previous defense under Saban is senior Rashaan Evans.

There’s also some lingering concern in the secondary over Minkah Fitzpatrick’s hamstring, which limited his effectiveness against LSU and Mississippi State and will likely keep him out against Mercer, and on the defensive line over Da’Shawn Hand’s knee, which forced him to miss three games and come off bench in the last two. The offense will also have to operate the next few weeks without OL Ross Pierschbacher, a mainstay up front with 40 consecutive starts at left guard, who’s dealing with an ankle injury at the worst possible time.

2. The Passing Game Is an Adventure. LSU notwithstanding, the offensive line has been a reliably dominant unit against everyone else in the run game. Pass protection, though, is another story: For the season, Bama ranks 105th in Adjusted Sack Rate, having allowed multiple sacks in each of its past five games. (On standard downs alone, i.e. run/play-action downs, Bama’s ASR ranks a shocking 126th.) Texas A&M’s pass rush dropped Jalen Hurts three times; LSU’s, four; Mississippi State’s, five.

Against LSU, pressure was such a persistent issue as the game wore on that it effectively prevented Hurts from throwing deep — by Pro Football Focus’ count, he was pressured 13 times and connected on just two of six attempts that traveled at least 20 yards downfield. The right side of the line, RG Lester Cotton and RT Matt Womack, is a massive run-blocking duo that has struggled against above-average speed rushers, which is turning out to be arguably Auburn’s biggest strength. The Tigers’ pass rush will be the best Alabama has faced, a very serious prospect given the results over the past month.

3. Who’s No. 2? Calvin Ridley is on the short list of the best receivers in the nation and stands a good chance of being the first wide out off the board in next year’s NFL Draft. He’s also the only target in the passing game Hurts can look forward to relying on on a consistent basis:

As far as Ridley’s production is concerned, those numbers are consistent with the ones he put up in his first two years on campus. (Overall catches are slightly down; yards per catch is significantly up.) What’s changed is the absence of a steady No. 2 receiver to balance the field: 10 games in, there’s no ArDarius Stewart or O.J. Howard anywhere in sight, or even anyone to fill the Richard Mullaney/Gehrig Dieter slot role. Instead, the Tide have resorted to a rotating cast of receivers that collectively shows up, randomly, about about three or four times per game.

Seniors Cam Sims and Robert Foster have 20 receptions between them, but only one touchdown; Foster, a former 5-star recruit in his last go-round in Tuscaloosa, has struggled with drops — his catch rate (40.9 percent on 22 targets) is the worst on the team — and has just two catches in the past month. Freshman Henry Ruggs III is a big-play magnet, having turned five of his six receptions into touchdowns, but has rarely flashed prior to garbage time; all but one of those scores have come in the second half of games Alabama already led by at least 14 points.

Ditto freshman DeVonta Smith, whose game-winning catch against Mississippi State was only his fifth reception of the year. The most touted of the freshman targets, Jerry Jeudy, had 11 catches in Bama’s first five SEC games, but has come up empty in the past two. And as receivers, the running backs and tight ends are running backs and tight ends — sophomore TE Morris Forristall suffered a season-ending injury in September, and no one else in either group has been targeted more than 15 times.

With Ridley (presumably), Foster and Sims all gone next year, the freshman class clearly has a bright future. (In addition to Jeudy, Smith, and Ruggs, Bama fans haven’t even laid eyes yet on 6-6, 210-pound Tyrell Shavers, a top-100 recruit who’s redshirting.) But there’s nothing yet that suggests that future is scheduled to arrive anytime in the next two to six weeks.

4. Not-So-Happy Returns. Special teams tend to go down as a footnote, but both of Alabama’s return units have been distinctly and uncharacteristically bad: The Tide are 12th in the SEC in punt returns and 13th on kickoff returns. Their only return of the year longer than 30 yards, punt or kickoff, was Minkah Fitzpatrick’s 39-yard return off an onside kick at Texas A&M. Worse, they’ve cycled through three punt returners (Ruggs, Travon Diggs and Xavian Marks) who have combined for eight fumbles or muffs — eight! — somehow losing only two. It’s been a few weeks, so ideally they’ve put that pattern behind them; if not, a loose ball on a punt is the kind of play that can change a big game in an instant.

5. Can the Sequel Top the Original? Deep down, the most unshakeable concern in the pit of Bama fans’ stomachs might not be tangible at all, but a sort of general anxiety left over from the 2016 team’s failure to finish on the biggest stage. That team was better than this one, more proven across the board, more consistent from week to week, and far less susceptible to exercises in negative nitpicking. It was barely challenged at all en route to Playoff, and poised to go down as one of the great college football teams of the modern era, right up to the moment (literally, the very last possible moment) that it wasn’t. In this sport, there’s no such thing as inevitability.

On paper, the 2017 team is virtually identical to last year’s, right down to the distribution of carries among Jalen Hurts and the running backs. The strengths are the same — Alabama remains a dominant rushing offense, as ever, and dominant defensively in almost every respect despite a major exodus of NFL-ready talent. But so are the potential Achilles’ heels: Aside from a substantially improved interception rate, Hurts has been essentially the exact same player as a sophomore as he was last year as a true freshman, when his production took a quantifiable nosedive in the postseason.

The secondary is largely the same one that ultimately wilted last year against Clemson, minus a first-round draft pick at cornerback (Marlon Humphrey), whose replacement is a former walk-on (Levi Wallace — who, in fairness, has been mostly outstanding in his first year as a starter). There are fewer playmakers on defense, generally, compared to the likes of Jonathan Allen, Reuben Foster and Tim Williams; there are potentially more playmakers on offense, but none aside from Ridley who fulfills the role week-in, week-out.

In the end, there’s a more or less even chance that we’ll look back and recognize that, yeah, obviously Alabama was the best team all along, just like their ranking said from start to finish. Every other contender has its own, even lengthier list of flaws, and aside from Oklahoma’s Baker Mayfield none of them has a quarterback playing anywhere near the level of Deshaun Watson.

There’s no better bet than the Crimson Tide. But as last year proved — and 2013, and 2014 — nothing is written in stone, by the media or anyone else.