SANTA CLARA, Calif. -- With newborn twins waiting at home and plenty of work to do on the field, NaVorro Bowman is feeling a great sense of responsibility this summer with the San Francisco 49ers.
That comes with the territory after Bowman's emergence last year as one of the NFL's best linebackers in just his second season.
Bowman went from a reserve role as a rookie to becoming a first-team All-Pro after the 49ers (No. 4 in the AP Pro32) moved him into the starting lineup last year. He quickly asserted himself as a force in the middle while helping San Francisco assert itself as one of the NFL's best defenses.
Now he's eager to build on what he and the 49ers accomplished last year while continuing to grow as a person.
"That's the way I'm going to stay humble and grounded," Bowman said Wednesday. "I have to take care of my responsibility, never be complacent, just continue doing the things that got me this far and success will continue to find me."
Success found Bowman in sudden fashion last year after San Francisco allowed former starter Takeo Spikes to leave in free agency.
Spikes was a respected veteran leader and productive tackler, but the 49ers felt comfortable elevating Bowman to take his place next to perennial Pro Bowler Patrick Willis in the middle of the team's 3-4 defensive scheme.
Bowman played so well from the start that some observers had difficulty telling him apart from Willis, a four-time All-Pro who had led the 49ers in tackles every year since joining the team as their first-round draft pick in 2007. Bowman replaced Willis as San Francisco's leading tackler and finished seventh in the NFL last year with 143 stops.
He also stepped up at key sequences throughout the season. Bowman established himself as a playmaker in San Francisco's Week 4 upset at Philadelphia that sparked the 49ers on their way to a 13-3 season, then twice had 13 or more tackles during a four-game stretch late in the season that Willis missed due to injury.
"When Pat went out, it was a wakeup call for me to carry the load, and I think that's what I did," Bowman said. "It was a challenge, and I stepped up to the challenge. I just wanted to put my foot on the gas and not be viewed as the young guy on the defense. I think that gained a lot more trust from the veteran guys."
At 24, Bowman is the youngest starter on a seasoned defense. But the 49ers still are placing their trust in him.
Defensive coordinator Vic Fangio said Bowman earned that trust last season and continues to impress coaches with his grasp and knowledge of the defense.
"He's much, much farther along this year than he was last year at this time," Fangio said. "He still has things to learn, but he understands football. Some understand it better than others, and he understands it good. You can talk to him at a high level when you're teaching him. You don't have to break it down and paint it by numbers."
The physical aspect has always been there for Bowman, the team's third-round draft pick in 2010. Once he got his starting shot last summer, he left no doubt that he could handle the responsibilities of the position as an every-down player.
Bowman was one of the few defenders who never came off the field for a unit that finished fourth in the NFL in total defense and second in rushing defense. He also proved to be a strong complement to the talented Willis, giving San Francisco arguably the top set of middle linebackers in the league.
Willis and Bowman were the two middle linebackers named to last season's All-Pro first team. Bowman earned his spot by mirroring the all-around excellence of his more renowned counterpart. He's doing more of the same now during San Francisco's training camp practices.
"He's very versatile as a linebacker," Fangio said. "He has really good movement and is athletic enough to be a good player in pass defense. He's really good in the open field and you saw some big plays there last year when he made some tough tackles. He's a really good tackler and he is tough."