Jones had been comfortable, winning separate national championships starting at right guard and left tackle, positions with their own intelligence, discipline and footwork. “It’s like tying your shoes with your left hand if you’re right-handed,” Warmack said. In that sense Jones has become ambidextrous, considered among the best — at guard, then tackle, and now center — without what others would consider enough sufficient time to master the intricacies.

“He has the size, and the makeup, and the ability to really play any position on the offensive line, and he has the adaptability to do it, too,” said his coach, Nick Saban, who has called Jones among the top five players he has coached. “And he has the psychological disposition that it doesn’t bother him.”

Jones had been a stout, dependable right guard, which required a quick first step, strong hands and cunning wit. Jones blocked defensive tackles outweighing him by 20 to 30 pounds in tight quarters, as if in a telephone booth. He started every game as a redshirt freshman in 2009, and Alabama won a national championship.

Image In addition to being a student of the game, Barrett Jones volunteers, as he did in 2011 in Haiti to build a basketball court. Credit... Courtesy of Leslie Jones

He played another season at right guard, but when James Carpenter was taken in the first round of the N.F.L. draft, Saban asked Jones to take his spot at left tackle. Jones relished the challenge.

Jones blocked the opponents’ best athletes — defensive ends who lined up wide of him and ran like linebackers — with no help, knowing that if he were to fail, his quarterback would be blindsided. If he backpedaled, he would lose ground. If he turned and ran out wide, he would lose the race. It was not natural, but like most great tackles, he trained to point his left toe to the sideline and his right toe upfield, and kick-slide out and back at an angle.

“It’s like a math game in your head,” Jones said. “You’re trying to think, how wide is he? Where’s the quarterback? So where’s the closest point I can meet him?”