The man who could fill in for All-Pro linebacker NaVorro Bowman recently discovered his high-profile temp job could last much longer than expected.

Last week, Jim Harbaugh said Bowman could miss at least half the 2014 season after he tore the anterior cruciate and medial collateral ligaments in his left knee in the NFC Championship Game.

In Overland Park, Kan., 49ers reserve linebacker Michael Wilhoite, who assumed Bowman would miss far less time, digested the news. And then he went back to work.

"It doesn't change the way I think, it doesn't change my motivation, it doesn't change the way I train. I'm going to do everything the exact same," Wilhoite said in a phone interview. "When Bo's ready to play, that's great for the 49ers. When he's not playing, I'm going to do my best to fill in and help the team win games."

The nose-to-the-grindstone approach has served Wilhoite well. He played at Division II Washburn University in Topeka, Kan., had a stint in the now-defunct United Football League and was a shoe salesman during a soul-searching stretch of football unemployment 26 months ago.

So it's a testament to his tenacity - and talent - that he's in his current spot: He's the logical candidate to fill in for one of the NFL's best players on one of the league's top defenses for a significant part of the 2014 season.

In 2013, Wilhoite, 27, did a commendable job subbing for another All-Pro, Patrick Willis, who missed two games with a groin injury. In wins over the Rams (35-11) and Texans (34-3), Wilhoite had 20 tackles and the 49ers allowed the seventh-fewest rushing yards (18) in franchise history at St. Louis.

Not that Wilhoite, whose 17 special-teams tackles in 2013 ranked second on the 49ers, has the temp spot secured. The competition to spell Bowman promises to be one of the top story lines of training camp. Wilhoite will battle Nick Moody, a 2013 sixth-round pick, and, perhaps, at least one linebacker not on the current roster. Last week, general manager Trent Baalke suggested the 49ers could bolster the spot in free agency or the draft.

"We're going to take a hard look to see if we need to infuse a little bit more competition into that position," Baalke said.

For his part, Wilhoite, an undrafted free agent who was barely recruited out of high school, isn't offended. He's accustomed to being a bit underestimated and, regardless of his background, he's well aware of how the 49ers operate.

"I would expect no less, especially from a championship-caliber team," he said. "I would never expect to go in anywhere and be handed anything. It's never happened like that in my life and I've never wanted it that way.

"On a team like this, it's like I tell everybody, it's not easy being great. It's not relaxing, it's not comforting, it's not easy work. In order to be great, it's going to be hard. It's going t0 be stressful. And there's going to be competition."

Before reporting for the team's offseason conditioning program, which begins April 21, Wilhoite will continue working out at a gym in Kansas City and driving 45 minutes twice a week to work with a personal trainer in his hometown of Topeka.

Before free agency begins March 11, he will also sign a contract to keep him with the 49ers in 2014. As a player with less than three accrued seasons, Wilhoite is an exclusive rights free agent, which means he can sign only with the 49ers. The team will re-sign Wilhoite at some point before the start of free agency.

When will he sign a new contract? Wilhoite is leaving that to his agent. He's too busy readying for what he hopes will be a significant role in 2014.

"I don't know how that (contract) works and I don't want to know how that works, to be honest," Wilhoite said. "All that I'm worried about is getting better."