Nebraska wasn’t supposed to be good in 2018.

Scott Frost knew his two-year transformation of UCF from winless to unbeaten represented an unusually fast rebuild. Taking Nebraska from 4-8 to good was always going to take more than one year.

But Nebraska is significantly worse than people and computers expected.

The preseason record projection by S&P+ was 5-7. Even tossing out a Week 1 rainout against Akron, Nebraska’s tracking to fall well short, with three wins now a reasonable target.

Why is the team so bad? Let’s get into it.

1. The run defense gets a lot of strikeouts ... until it gives up a grand slam.

The Huskers have six upperclassmen in their starting front. Most were at least three-star recruits.

Most of the time, the run defense avoids taking on water. After Week 4, the Huskers were 29th out of 130 FBS teams in marginal efficiency against the run. (That’s how often runs are successful against them, relative to other defenses.)

The Huskers were ninth in defensive opportunity rate, the percentage of carries that reached five yards against them, at 34.2 percent. They’re 18th in stuff rate, the percentage of runs they stopped without gain.

These are hallmarks of a solid rush defense. But then the breakdowns come.

The Huskers were 129th in marginal explosiveness allowed, meaning that when opponents pull off successful runs, they’re huge. The Huskers let up 14 runs of 10-plus yards, six of 20-plus, three of 30-plus, and three of 40-plus, ranking pretty poorly in each despite having played fewer games than most teams.

On the drive that put Troy out of reach, they held up well to wanton shifts:

Interior pressure here by the nose tackle, and a nice job holding up on the outside to keep contain, allowed Big Red to fill the alley.

Same thing here. They don’t take the bait of motion, communicating and executing a nice scrape exchange — a defensive end crashing down to play the running back, and a linebacker looping behind him to play the QB run — to limit the damage. Linebacker Will Honas (No. 3) steps up and avoids a guard who has climbed to the second level, then makes a strong tackle.

But as the drive wears on, Nebraska doesn’t bend. It flat-out breaks.

Troy spreads the field and uses motion to get the perfect box look: five Nebraska defenders on five Troy blockers. Then, a linebacker flows out of the play post-snap. That’s good scheme meeting a breakdown.

Plus, Nebraska’s linemen just got mashed on the 10th snap of a drive in the fourth quarter.

But this was on a third-and-9 coming out of a timeout. Instead of holding up, the Huskers allowed a chunk play ...

... and then got gashed again on the next two plays.

One was a penalty and called back. Then Troy again used motion to go up two scores. Notice both safeties rotating at the snap — which they’re likely coached to do — sending one flying to the perimeter and out of the rush lane.

2. The defense can’t get off the field, despite forcing lots of third-and-longs.

A wild stat: through Week 4, Nebraska required opposing offenses to convert on third-and-7 or longer on 70 percent of all defensive third downs. That’s No. 3 in the country. The average distance for opposing offenses on a third down against Nebraska was 9.7 yards, which was No. 1.

And yet Nebraska gave up a first down on 28 percent of those plays, No. 98 in the country.

The Huskers force the offense into hard spots, then let them off the hook.

3. The offense also gets into third-and-longs and is also terrible in them.

The average third-down distance for the Husker offense was 9.1 yards. That ranked them No. 125 in third-down difficulty. And they’re really bad in those spots, converting just 16 percent of the time, ranking 121st.

They’re 118th in overall third-down conversion rate, so it’s trouble when they don’t move the sticks early.

(Some hope here: Frost’s UCF offense was great on first down.)

Third downs are long because of failures on preceding downs. Take this from the Michigan game on second-and-long:

Maybe freshman QB Adrian Martinez should stand in the pocket, because if Greg Bell (No. 25) can get the corner, it’s a chunk play. But Martinez gets skittish, rushes the throw, and misses.

Now it’s a long third down, so Michigan pins its ears back:

When pass rushers know they can just go after the QB — whether Martinez or less-mobile backup Andrew Bunch — they rack up takedowns. Nebraska QBs got sacked on 12 percent of their dropbacks through three games, fifth-worst in FBS.

Watching Nebraska play at Michigan might have made you genuinely fear for Martinez. Rashan Gary is going to do this to a lot of offensive linemen, but holy hell:

Martinez does really well to turn this from a 7-yard loss to a 2-yard gain.

Second down on the same series brings more good things for Nebraska. The Huskers sprint out, a blocking scheme used to neutralize dominating pass rushes. It also simplifies reads for Martinez by cutting the field in half.

It’s third-and-short now. Hell yeah!

Now, let’s sprint out the other way, keep Michigan on their toes and extend th—

Bad pass protection is a killer, no matter the down and distance.

4. The running game is ahead of what Frost had in his first year at UCF, but Nebraska’s backs and blockers have a long way to go.

In 2017, Frost’s UCF offense took off in part because of how well the Knights incorporated various running schemes. It takes time to build the communication and execution that requires.

“I told ‘em [in 2016], ‘Where we get to the point where we run our basic stuff and get yards, then all of our other stuff is gonna be even more effective,’” Frost told SB Nation then. “[In 2016], at times we struggled with our basic stuff, and some of the trickier things didn’t work as well, because we were behind the chains and we were putting pressure on our defense.”

The good news: the Huskers’ running game isn’t as bad as UCF’s was in Frost’s first year. The Huskers are 81st in yards per carry and around 60th in advanced efficiency and explosiveness stats, while UCF was in the 110s and 120s.

The bad news: that’s still not good.

When Frost says “we couldn’t get the one block we needed all day,” like he did after that Michigan debacle, here’s what he’s talking about:

This is as basic a run play as there is, but it doesn’t hit because of backside pressure allowed by the tight end. Nebraska’s left guard and tackle create a hole, but it gets closed up anyway.

“We couldn’t line up and run our most basic play 2 or 3 yards,” Frost said.

5. Nebraska’s field position is overwhelmingly bad.

The average Nebraska drive has started at the Huskers’ 25.9-yard line, No. 124 in average offensive field position.

The average opponent drive has started at the opponent’s 34.5, ranking No. 126.

The kickoff unit’s been good, but that’s only so useful when you’re rarely kicking off.

The punting unit’s been terrible. Caleb Lightbourn has punted for a fine average of 43.4 yards. But while the Huskers are 39th in punt distance, they’re 113th in average return allowed — nearly 18 yards.

Whether Lightbourn isn’t getting enough hang time, his teammates aren’t tackling well, or it’s a mixture, is unclear. But a 31-yard average net punt doesn’t help anything.

6. And they’ve made dumb mistakes, as lots of teams might when just getting started under a new staff.

For example: late in the Michigan blowout, a touchdown got wiped off because a slot receiver had lined up on the line:

The outside receiver was also on the line, making the slot man ineligible to go downfield or catch a pass. It didn’t change the game’s result, obviously.

A more consequential error late in the loss to Colorado was DB Antonio Reed’s personal foul on a third-and-24:

That dovetailed with bad third-and-long defense. And it set up a game-losing TD.

7. Underpinning all that, Nebraska lacks QB depth.

Tanner Lee turned pro after 2017. Former four-star Tristan Gebbia transferred after losing the job to Martinez.

So, Bunch, a walk-on, is the No. 2 quarterback. Martinez got hurt in game one during a hit Nebraska felt was dirty. It’s hard for anyone to succeed while starting a walk-on QB.

These things are fixable. They’re just not all fixable in a year.

That’s why S&P+ gives the Huskers a 52 percent chance of winning two games or fewer.

Martinez could still turn into a star, recruiting is going well (the Huskers have a top-25 class at the moment), and Frost’s recent evidence of a turnaround are all cause for hope.

Things will get brighter, though they could get still darker first.