It was a tense Sunday morning at the Kentucky football complex. The coaches were still shocked from the night before. They had run into the locker room at halftime with a 24-7 lead over rival Louisville, confident they would secure the win necessary for postseason eligibility. But in the second half, the Cardinals turned to their backup quarterback, a freshman named Lamar Jackson, and he vaporized the Wildcats with 31 unanswered points.

Now Kentucky’s season was over, the staff was gathered in a conference room, and Coach Mark Stoops was thundering, “I’ve never even heard of him!”

“At the time, none of us knew who Lamar was,” then-defensive coordinator D.J. Eliot lamented.

Four seasons later, everyone in football knows Jackson. He is the likely NFL MVP and the leader of the league’s most dangerous offense for the AFC’s top-seeded Baltimore Ravens, who open their postseason Saturday night by hosting the sixth-seeded Tennessee Titans. He is arguably the league’s most dynamic player, with a rocket arm and explosive legs, and his success has been an achievement appreciated by almost everyone — except the small number of men who have ever tried to stop him.

“You felt helpless,” Suncoast High’s Jimmy Clark said.

“They’d still be scoring points if we were still playing,” Marshall’s Chuck Heater said.

“BIG TIME HEADACHE!!” an NFL defensive coordinator wrote in a text after facing Jackson this season.

These men still marvel at how Jackson broke their game plans. There is a general philosophy to limit damage — contain him in the pocket, force him to throw — but no matter how well the defense prepared or executed, Jackson often emerged the victor anyway. (When asked how he planned to stop Jackson this week, Titans Coach Mike Vrabel quipped, “Other than try and tie his shoelaces together?”) The quarterback has, at every level, left in his wake a trail of exasperated opposing coaches.

It started in high school. Donald Hanna, whose Village Academy team faced Jackson’s Boynton Beach High squad, had heard about a kid who stood out even in the youth football hotbed of South Florida. Teams game-planned not to stop Jackson but to outscore him, an approach one coach compared to going up against Michael Jordan. Hanna suspected Jackson was the type of speedy quarterback common in the area, but during a spring scrimmage in 2013, he realized how wrong he was.

“No matter how many people you assigned to him, he made them miss,” Hanna said.

It didn’t dawn on Hanna until weeks later that his school had helped birth the legend of Lamar Jackson. One day, players rushed into his business education class pleading, “Look!” Hanna watched as, on screen, Jackson eluded one Village Academy defender, outran a second and timed up a third so that, just as he was about to deliver a crunching hit at the goal line, Jackson froze. The defender whiffed and sailed out of frame. It looked like a cartoon.

The play — the audacity, the jarring athleticism — had gone viral, racking up millions of views on YouTube, Vine and a popular video blog among teenagers usually reserved for brutal fights.

“It hit WorldStar, and I was like, ‘Oh, s---,’” the coach said.

That fall, ahead of another game against Jackson, Hanna changed his defense to an approach that would be replicated and tweaked against Jackson in college and the NFL. The coach didn’t want Jackson to beat his team by running, so the defensive linemen rushed at the offensive linemen instead of around them. Hanna wanted to collapse the pocket, close running lanes and force Jackson to beat Village Academy with his arm. The young quarterback did, but Hanna saw it as an improvement that “we actually kind of held our own.”

College coaches learned to fear Jackson’s ability to score from anywhere. Syracuse defensive coordinator Brian Ward was his first power-conference opponent after Jackson’s debut win over Kentucky and his Music City Bowl torching of Texas A&M for 553 yards and four touchdowns, and Ward knew the quarterback was more athletic than his defenders. Ward brought both safeties closer to the line of scrimmage in a “Cover Zero” look and gambled that Jackson wasn’t a good enough passer to make him pay for leaving the deep middle of the field wide open. The idea was more bodies, less space.

The concept worked, Ward thought, but the defender or two assigned to Jackson still struggled to lay even a finger on him. The quarterback totaled 610 yards, five touchdowns and one Heisman Trophy-defining leap over a defensive back — numbers that said less about the game plan and more about the talent gap between Syracuse and other college teams. Clemson and Houston employed similar schemes but tweaked them with disguises, creative blitzes and press coverage from their defensive backs. The Cougars sacked Jackson 11 times.

Eliot, the Kentucky defensive coordinator, sampled those approaches the year after Jackson ended his season. The Wildcats willed Jackson to give up the ball however possible, sometimes sending two defenders at him while ignoring the running back on zone-read plays — on which Jackson had the option to hand off or keep the ball himself — to keep Jackson from running.

The idea was to let Louisville “get five [yards], not 50.” Kentucky’s defense hit Jackson often, and on the quarterback’s last significant snap of the game, a big hit forced him to fumble in the red zone. Kentucky pulled off the win as a 28-point underdog.

“It felt good,” Eliot said.

NFL teams used those approaches as templates last season, when the Ravens named Jackson their starting quarterback in Week 10 of his rookie year. But the Ravens countered by overhauling their offense to minimize Jackson’s relative weakness (throwing) and accentuate his strength (mobility). They won six of their final seven games and sneaked into the playoffs, where Los Angeles Chargers defensive coordinator Gus Bradley baffled Jackson better than anyone in pro football before or since.

The Chargers used a radical game plan with seven defensive backs to equal Jackson’s speed. No team had tried anything like it all season, and Coach Anthony Lynn asked Bradley before the game: “Are we insane, or what?” The Chargers suffocated Jackson for most of the day and overcame the approach’s glaring weakness — less size against Baltimore’s bruising running backs — with a superlative game from the defensive line.

That was the last time the NFL paralyzed Jackson. The Ravens rebuilt around the quarterback this offseason, promoted Greg Roman to offensive coordinator and this year lit the league ablaze. The quarterback’s improved arm, the offense’s varied personnel packages and his running ability have made Jackson almost impossible to defend. Former Los Angeles Rams defensive coordinator Wade Phillips called Jackson “Michael Vick Plus.”

This progress leaves Hanna, the Village Academy coach, chuckling. He has coached dozens of college players and one who made the NFL, but he never believed Jackson’s game would translate. The coach watched in early November as Jackson dismantled one of the best defenses of the past three decades, the New England Patriots', led by one of the best defensive minds ever, Bill Belichick.

He ended that game thinking back to 2016, when Jackson tore up his beloved Florida State for 362 yards and five touchdowns. He had texted his defensive coordinator right away: “It’s okay, man. We’re not terrible coaches!” Now, even if he still loses sleep every once in a while thinking about how to defend Lamar Jackson, it’s a comfort to know he is not alone.

Adam Kilgore contributed to this report.