SANTA CLARA -- The fullback might be a position on the NFL’s endangered list, but Kyle Juszczyk is thriving.

A segment of the uninformed criticized the 49ers for overspending to acquire Juszczyk on the first day of 2017 free agency without understanding how coach Kyle Shanahan planned to incorporate two-back personnel groupings into his offense. And while the 49ers have achieved success with numerous running backs carrying the ball, the man leading the way has remained consistent.

As San Francisco breezed through the NFC side of the playoffs with a varied running attack, Juszczyk rarely came off the field. He did not had a rushing attempt or reception. But while playing 90 of the 49ers’ 119 offensive snaps, Juszczyk’s contributions were enormous for a team that advanced to Super Bowl LIV against the Kansas City Chiefs on Sunday, Feb. 2.

Perhaps nobody on the 49ers’ offense, other than quarterback Jimmy Garoppolo, has more responsibilities in the execution of the team’s offensive game plan than Juszczyk.

“We put a lot on him, and we haven't put too much on him, yet,” Shanahan said. “So he's been able to handle it each time. I'll say that's because of his Harvard education, but he's a hell of a football player who doesn't get nervous about anything, and he works very hard throughout the week to understand everything.”

Because the Niners' run game is so varied, Juszczyk has to understand the nuances of every play, and he must be able to adjust on the fly to ensure that he blocks the defender constituting the biggest threat to running backs Raheem Mostert, Tevin Coleman, Matt Breida or Jeff Wilson.

Juszczyk said he deals with a vast amount of verbiage on a weekly basis. When he initially sees the offensive game plan early in the week, it might look overwhelming at first. But his Ivy League education pays off as he, without fail, is able to learn his assignments in the classroom, then carry it over to the practice field and into games.

“After a day or two of being able to absorb it, usually I don’t have a problem with it,” said Juszczyk, who has proved to be a bargain with his four-year, $21 million contract.

Juszczyk, who missed four regular-season games due to a knee injury, made a significant impact in every aspect of the offense even without regularly touching the ball. He carried just three times for 7 yards and caught 20 passes for 239 yards and one touchdown.

The fullback was selected to his fourth consecutive Pro Bowl this season, although he obviously won't be participating. He might not have a lot of competition for selection into the event because few teams actually deploy a fullback these days, but that does not minimize his importance to the 49ers.

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Said Mostert: “Our coach always explains it to us in the meeting room, ‘I don’t want guys who are necessarily the strongest or the fastest, the ideal fullback; I want a guy who’s a smart football player, because I know a smart football player won’t beat this team up.’ That’s what Juice is. He’s a smart football player. He gets the job done every time he goes out there.”

Because of Juszczyk’s versatility, the 49ers have the ability to be multi-faceted with their run game. You name it, the 49ers do it, as Juszczyk explains, from gap scheme to wide zone to misdirection, traps, counters. The 49ers are able to adjust because their fullback is the best in the business.

“There aren’t too many defensive schemes that are built to take away every single one of those,” Juszczyk said.

NBC Sports Bay Area feeds your hunger for 49ers Super Bowl coverage with special editions of “49ers Central” all week (5:30 p.m. Monday and Wednesday; 8:00 p.m. Tuesday and Thursday; 6:00 p.m. Friday).