The images of Johnny Manziel dancing in the pocket and Trevor Knight evading the rush stick with you.

You close your eyes and watch Nick Marshall sprinting to his left before pulling up to pass.

You see Cardale Jones and Ezekiel Elliott running at will by the defense and on to the national championship.

The moments were few and far between in the grand scheme of things, but they came often enough in the past few years that they were impossible to forget. Alabama's defensive line, the impossibly big maulers and space-eaters we came to expect under coach Nick Saban, struggled in important games the past few seasons.

They were, simply put, a step slow.

The pace of play allowed for too wide rushing lanes and mobile quarterbacks sidestepped the pressure too often and waited for a receiver to be open, which they inevitably were. You saw it all last season in a three-game stretch against Auburn, Missouri and Ohio State in which the defense gave up an uncharacteristic 493.3 yards per game.

The search for answers led to one of the biggest missteps in Saban's tenure in Tuscaloosa, Alabama, when he signed Jonathan Taylor, a defensive lineman kicked out of Georgia. Within weeks, Taylor was sent packing from Alabama following an arrest on charges of domestic violence.

Led by Jonathan Allen and A'Shawn Robinson, Alabama's defensive line bottled up Treon Harris en route to another SEC title. Butch Dill/USA TODAY Sports

Part of Saban wanted to give Taylor a second chance, but part of it was an attempt to bring in another talented defensive lineman to help the Tide win a national championship.

As it turned out, the answers were right in front of Saban. He never needed Taylor.

He had three potential first-round picks. He had a rotation whose depth would become the envy of all other coaches. And he was eventually able to put it all together to create one of the best defensive lines college football has seen in recent memory.

Arkansas coach Bret Bielema said it compares only to the NFL.

"They all look the same," he said. "I swear, it's a machine that creates them."

But, in fact, the machine took time to reach this level of production, leading the FBS in rushing yards allowed per game and sacks. It took a new position coach, a new attitude and a new dynamic in the weight room.

"It's crazy, man," said safety Eddie Jackson. "Watching those guys, they're workhorses. They come in every day and work. They don't want no big plays. They don't want to allow a yard."

Meet the firing line

The freak athlete

A'Shawn Robinson was the biggest little kid in a state where everything is larger than life.

He grew the earliest beard, the meanest scowl and the biggest body of anyone in his class. He developed into one of Texas' top prospects at Arlington Heights High, a 6-foot-4, 300-pound teenager who played both offensive and defensive tackle, and probably could have done more if his coach, Ged Kates, had asked him.

"A big-time head coach came in after football season," Kates recalled. "He said he'd love to see him and I said we could walk over to the gym and see him at basketball practice. We walk over there and he does a three-man weave and a full-court layup drill. He watched him run down the court and back and dunk it and said, 'Coach, he's going to get a lot of scholarship offers. You remember his first one came from me.'

"They have 12 defensive linemen that would start for anybody in the country." Mississippi State coach Dan Mullen

"That was it. He didn't even [have to] put on tape him playing football."

You saw that raw athleticism when Robinson blocked an extra point against LSU this season. He lined up in a three-point stance a yard or so away from the center, took one step when the ball was snapped, gathered himself and leaped over the line, landing on two feet before immediately jumping again to block the kick.

All that was missing was a sand pit and one last leap to complete an Olympic-quality triple jump.

In that same game, Robinson was used as a lead blocker on offense, paving the way for tailback Derrick Henry.

"He really can do whatever he wants on the football field," said linebacker Dillon Lee.

The hidden gem

Jonathan Allen was an SEC All-Freshman Team snub in 2013. Then he was overlooked again in 2014, failing to make the coaches' All-SEC teams.

Robinson has dominated the headlines, but Allen is every bit the same caliber player.

The former No. 2-ranked prospect in the state of Virginia arrived at Alabama's doorstep ready to produce. He played in 13 games as a freshman in 2013 before becoming a starter in 2014, finishing second on the team in tackles for loss (11.5).

More importantly, he was the kind of every-down player Saban needed. At 6-foot-3 and 283 pounds, he could play the run as well as rush the passer.

Through 13 games this season, he leads the team in tackles for loss and sacks.

Jonathan Allen's coming-out party against Mississippi State stamped him as a dominant force along Alabama's defensive line. Matt Bush/USA TODAY Sports

If fans didn't know his name before, then they surely heard it after Alabama played Mississippi State in mid-November. It was then that Allen was named SEC Defensive Lineman of the Week.

Saban joked that he received the award for a collision in which Allen gave his coach a scar, but really it was in recognition of much more: A week after taking a pounding against LSU, Allen was all over All-SEC QB Dak Prescott, sacking the dual-threat passer three times.

The late bloomer

Jarran Reed wasn't even ranked by ESPN coming out of high school. Without the necessary grades, he had to go to a prep school and then a junior college.

At East Mississippi Community College, coach Buddy Stephens saw a potential star in Reed. But Reed's first year at EMCC wasn't what it should have been. He signed with Florida, but had to stay at EMCC for another year to get his grades in order.

As it turns out, that extra year was a blessing in disguise as that spring D.J. Pettway arrived on campus.

Pettway, who was kicked out of Alabama after being involved in an on-campus assault, immediately became one of Stephens' best pass-rushers. He also became Reed's roommate.

"He played mad his senior year. He played with an attitude," Stephens said of Reed. "He saw how close he was when D.J. got there. I think he saw how close he was to being really good, and I think that pushed him over the edge.

"You can see him growing in self-confidence from the way he played last year to the way he played now," he added. "It's almost like watching the stadium fill up for a ballgame. You can just tell he's ready to explode."

Today, Reed is arguably Alabama's most consistent lineman.

"When he's on the field, he's nothing but business," said center Ryan Kelly. "When he speaks, everybody listens, even me."

Strength in numbers

The thing Saban likes most about this line and the thing that makes it one of the best in recent history, is its depth and diversity.

Before the season began, Saban said the rotation had the potential to go 10 deep. It felt like exaggeration, but it was fact.

Beyond the trio of potential first-round picks, there is a slew of former four- and five-star recruits who fill valuable roles.

Darren Lake and Daron Payne are 300-pound road-graders who have held star running backs like Leonard Fournette, Nick Chubb and Alex Collins in check. Payne, despite being a true freshman, has started a handful of games, and is the rare thing Saban has been searching for: a nose guard who is quick enough to rush the passer.

Then there are Ryan Anderson and Tim Williams, the speedy hybrid end/outside linebackers who specialize in disrupting the passing game.

"The quarterback is the head of the snake," said Williams, who has 9.5 sacks despite no starts this season. "I feel like if I hit him ... they wonder if he'll get up or not."

If Williams isn't sprinting off the edge and Alabama goes with four down linemen, then there are ends like the uberathletic Dalvin Tomlinson or former All-SEC freshman selections Pettway and Da'Shawn Hand. They all look the same: roughly 6-foot-3 and 270 pounds with the ability to stay gap-sound against the run or pin their ears back and rush the passer.

Said Mississippi State coach Dan Mullen: "They have 12 defensive linemen that would start for anybody in the country."

When asked about the front seven as a whole, Florida coach Jim McElwain lost count.

Jarran Reed has gone from late-blooming juco transfer to indispensable force -- and likely first-round pick -- for Nick Saban. Tim Heitman/USA TODAY Sports

"The front seven? I think it's the front 30, how many guys they've got," he said before the SEC title game earlier this month. "I just hope our offensive line, their knees don't crack together from shaking as they got to play against those guys. They just keep rolling them through there."

There weren't any broken bones when Alabama beat Florida, but there were plenty of broken spirits as the Tide racked up five sacks and limited Florida to 15 yards rushing.

Adapting to a changing game

With the exception of Payne, though, the defensive line is the same as it was a season ago when it was good, but fell short of the greatness we're witnessing today.

What has changed is an emphasis on conditioning and a new position coach who brought a no-nonsense approach to the unit.

The game has changed during the past 10 years. How Alabama looked at its defensive linemen had to as well.

With the rise of the hurry-up, opposing coaches no longer run away from the biggest guy on the field. Instead, they try to run and run and run until the big boys can't run any longer.

"You look at a guy in the NFL come in with a 50-inch waist come in and play one play and go off the field," said one Pac-12 offensive coordinator. "Well, if he comes on the field in college, he plays one play and we're going to run the next snap before he can get off the field."

It took time, but Saban got the memo. He told ESPN this offseason that while the 340-pound Terrence Cody was "unblockable" at Alabama from 2008 to '09, he "couldn't play for us now."

So Alabama went to work this offseason on what Tomlinson described as an "intense conditioning practice" in order to "be prepared for the fast-ball offense."

Robinson lost six pounds. Reed dropped 10. Lake lost eight pounds and, according to one report, Payne shed 25.

Allen, on the other hand, gained 15 pounds of muscle.

"It's really helping us all out," Reed said, "because we're playing everywhere and we're rotating with each other. So when he goes inside, he's big enough now to play inside. We trimmed enough weight to go outside."

Said Saban: "You look at a guy's performance relative to how much he weighs. When a guy weighs 307 pounds and he can move and sustain and rush the passer and all those things, and when he weighs 318 pounds he can't do it. It's not rocket science."

And, really, simplicity is one of the reasons Alabama's D-line has made such significant strides.

When Bo Davis returned to Alabama as defensive line coach this offseason, he didn't try to reinvent the wheel. Rather, he tried to make it spin faster by removing its extraneous parts.

Tomlinson said in fall camp that Davis put a bigger emphasis on reacting and thinking less after the snap.

"He wants us to be more aggressive, more physical on the defensive line," he said. "And also quicker with everything and all our reactions."

"He's made us better players," Robinson added, "much better players than we were last year. Just making us the animals that he's made us."

Alabama had never finished in the top 10 nationally in sacks under Saban and now the Tide are No. 1 in the country. At the same time, the gap between Alabama and the No. 2 rush defense is nearly 10 yards per game.

Whether it was Georgia, Texas A&M, LSU or Florida, the defensive line has dominated each top-10 showdown since an early-season loss to Ole Miss. Even Auburn's no-huddle offense was contained.

Now there's only one box left to check and one memory to overcome: the playoff.

Jones, Elliott and Ohio State got the best of Alabama's defense last season. But maybe that loss was just the push the Crimson Tide needed.

Now Michigan State gets to deal with the results.

"They're very big, very talented, very fast," said MSU QB Connor Cook. "Anything you want on a defense they have. Watching film, it almost looks like an NFL defense. Just the size that they have up front and the physicality they play with. It's going to be a challenge for sure."