Alabama freshman Jonah Williams is impressing teammates and coaches for being a keen student of the game. (Albert Pena/AP)

ATLANTA – Alabama coaches woo most recruits with ostentation, leading them through the gleaming players’ lounge for games of pool and air hockey. They knew better when it came to Jonah Williams. Last year, as a high school senior, Williams visited Alabama’s campus the weekend the Crimson Tide beat Tennessee. After the game, coaches ushered him and his father into a place recruits rarely consider: the film room. They placed a clicker in his hand, and Williams lit up.

“I had never had, like, really good film like that before,” Williams said. “So I’m just like, ‘Look at the left guard here!’ I was just eating it up. I just loved it.”

As Alabama’s machine rolls into the College Football Playoff semifinal Saturday against Washington, it will feature a curious cog in Williams. Quarterback Jalen Hurts has become perhaps the most acclaimed true freshman in the country. But the defending national champions, a program that hordes top recruits and has won 25 consecutive games, also start a true freshman at right tackle. It’s a position rarely entrusted to a player without experience or extra years to bulk up. Of all the top-shelf offensive linemen Alabama has accumulated, one of the best is a 6-foot-5, 296-pound “guy who’s still squeezing pimples,” Alabama offensive line coach Mario Cristobal said.

Williams wears his football dorkhood with a mix of pride of sheepishness, a self-described “film junkie” who tries not to share the full extent of his tape-watching with teammates. During Alabama’s four weeks off to prepare for Washington, Williams has watched every game Washington played in recent seasons, mostly by himself in his dorm room.

“It can be fun,” Williams said. “My friends would make fun of me for saying that.”

“He’s a football addict,” Cristobal said. “I mean that in a good way.”

In most every situation, Williams reverts to film for comfort. Before Alabama played USC to open the season, Williams watched Alabama’s 2014 season opener against West Virginia to see how then-freshman Cam Robinson handled his debut. He chose not to ask Robinson, now Alabama’s left tackle, about the experience.

“I never really told him I went back and stalked his film from three years ago,” Williams said.

Williams developed a weekly routine. He would find three or four games Alabama’s opponent had played against a similar offense and watch every play on his iPad. When the offense comes to the line in a certain formation, he stops the tape and determines which player he would block, and which technique he would use, on five or six plays Alabama runs out of the same formation. He presses play, studies how the defense’s safeties rotate, then says aloud, to himself, how it would change his assignment.

“I think when you visualize all that mentally before the game, you can just kind of play,” Williams said.

Williams discovered his penchant for film study after his family moved from Atlanta to Folsom, Calif., after his high school freshman season. At Marist High in Atlanta, Williams ran the triple option, which meant his assignment rarely changed from play to play, making studying pointless. When he moved to Folsom, Coach Kris Richardson ran the spread, which caused defenses to react in varying ways.

During a teaching assistant period, Williams would sit with Richardson, also the school’s physical education teacher, and watch him diagnose plays on an iPad. “That’s when I started realizing that it could put me ahead of other people,” Williams said. He began to understand how a safety’s pre-snap movement could tip off a defense and the importance of identifying the strong-side linebacker.

Major colleges began taking interest in Williams during his junior season. Cristobal, one of Alabama’s best recruiters, noticed Williams and took the lead in trying to sway him.

“I expended every possibility as allowed by the NCAA to go out there and see him,” Cristobal said. “On film, he sticks out. It looks like something you’d see in ‘Terminator,’ just people bouncing off of him. I think my 7-year-old could have watched the film and said, ‘We need to go get this guy.’ ”

The more Cristobal learned, the more he wanted Williams. Administrators and coaches vouched for his honor-roll grades and tireless work habits. From most recruits, Cristobal would receive a short note after he asked them about a game. Williams would send him back multiple paragraphs, dense with technical insight and coaching lingo.

“His text messages were, ‘Well, I had a four-eye, and I jab-stepped him to loop him, but he didn’t fall for the jab-step, so he came outside because he was a two-gapper, but I got my hands inside, and I pressed on the sternum and I created leverage,’ ” Cristobal said. “I’m like, ‘Alright, I’m looking forward to attending your clinic one day.’ ”

Other schools, trying to beat out the Crimson Tide for his commitment, told Williams he may not be able to start immediately at Alabama because of all the talent already there. It was probably true, but it never mattered. “I don’t want to waltz into a job,” Williams said. “I want a challenge. If I can’t earn the job, I don’t really deserve it.”

Williams graduated early so he could enroll in Alabama last spring, which allowed him to practice with on the Tide’s scout team during their preparation for last year’s national title game. Those practices and a strong spring made Alabama consider him as a starting tackle. Last summer, he convinced them.

All year, Williams has awed coaches with his precision and intellect, both the product of his film study. Cristobal said he has not made a single mental mistake all year, and he has never seen a true freshman with better technique. “If he’s supposed to take a six-inch step,” Cristobal said, “God forbid he should go six inches and a millimeter.”

Eight times this season, Alabama coaches named him the Tide’s offensive player of the week. Not among freshman. For the entire offense. “You forget he’s a freshman at times,” defensive end Jonathan Allen said. “He’s gonna be something fierce.”

Williams said it feels “surreal” to be in Atlanta, the place he grew up, starting so early in his career for a team some family members grew up idolizing. Family and friends will watch him Saturday. And afterward, to be sure, Williams will be watching, too.