"I'm just trying to do whatever gives us the best chance to win," Shanahan told reporters on Tuesday. "I think a fullback helps."
Fullbacks seem like a vanishing breed in the NFL. More and more NFL teams enter the regular season without a fullback. The 49ers have one of the best in the league on their roster, and they paid a healthy sum to acquire him last year.
Kyle Juszczyk earns an average salary more than double that of any other NFL fullback. He was one of the 49ers' top targets in free agency last year. Being touted as an "offensive weapon" by general manager John Lynch may have contributed to the unfair expectations surrounding Juszczyk.
"I think some people thought maybe he was going to lead the team in stats and things like that," Shanahan said. "If he was, he wouldn't be a fullback. He would be treated as a second halfback or the second tight end. He is a fullback because he's a very good blocker, which makes defenses honor that.
"But the versatility, how smart he is, that he can go out and catch passes, and he can line up anywhere without a ton of reps, it allows us to do anything we want out of two backs."
The 49ers signed Juszczyk to a four-year deal last year worth up to $21 million, and there is no regret in playing top dollar to acquire him.
"Kyle was someone we were going to get," Shanahan said. "He was the best fullback in the league, and we were going to go get whatever that market dictated. I know we had to compete with a few other teams, but we thought he was going to be very important."
Shanahan was very pleased with the fullback's performance last season, which, like many offensive players, saw a jump once Jimmy Garoppolo took over as the starting quarterback. Garoppolo enjoys having Juszczyk on offense because of what it does to opposing defenses. With so many teams opting not to have a fullback on their rosters, seeing one in the 49ers' backfield gives pass rushers something else to worry about.
"It's tough for a defense," Garoppolo said on Tuesday. "It's looks that they don't usually see very often compared to the 11 personnel and things like that, so it just keeps them on their toes, I guess."
Juszczyk brought a rare skillset to the 49ers offense, which is what made him so valuable to Shanahan and company. Versatility is an essential trait for 49ers players to have and Juszczyk perfectly fits what the team wants out of the position.
"He's more agile," Garoppolo said. "He can run routes from the backfield. He can run routes split out. That's a rare thing to find in a fullback, and he has good hands on top of all of that. It's a unique position that he's in. He takes advantage of it."
Shanahan believes having a fullback as talented as Juszczyk keeps the defense honest. Having one, however, isn't always without its drawbacks. That's why having a player like Juszczyk minimizes those drawbacks.
"I feel like when a fullback is in there, if you want to run the ball, you can, and the defense knows that," Shanahan said. "Even if they want to do certain things, you have the right type of blockers and the numbers where you can dictate how the game goes. I think defenses know that, so it limits a lot of the stuff they do.
"The negative can be when you have a fullback in all the time, and they know you're in two-back all the time, that there's only a couple of eligibles that they have to worry about. It's a lot easier to cover people. But that's what's the advantage of someone like ours, that just because our fullback is in, you don't know whether we're in two-back or one-back, which, I think, puts pressure on defenses."
Juszczyk allows Shanahan to do what he wants with his receivers and tight ends. If they are running an outside zone and there is no fullback, it becomes tougher to stop the pressure from opposing defenses, Shanahan explained. With a fullback, the 49ers don't need to bring the receivers in to block if they don't need to.
"When the fullback's in the game, the receivers can stay out wide and stay on the corners, and the fullback can take care of the safeties," Shanahan said.