Because 2-14 teams can’t address all their problem areas in one offseason, the 49ers might rely on a player with a track record of unreliability to play a vital spot in 2017.

The position: the so-called “Leo” defensive end in their 4-3 defense, which is reserved for the team’s most ferocious pass rusher.

A leading candidate: Aaron Lynch, 24, who reported for the offseason program overweight after ballooning to offensive-lineman proportions last year.

Last week, Lynch said his weight is in the 280s and his goal is to play between 260 to 270. In 2016, Lynch said he weighed around 300 pounds in training camp before he served a season-opening, four-game suspension for violating the NFL’s drug policy.

“I came in heavy, but my working my ass off to get down to where my coaches want me to get down to,” Lynch said last week. “And where I feel like I would be best (to) give everything I can for my team.”

Lynch’s team has added 50 faces to its 90-man offseason roster since head coach Kyle Shanahan was hired in February. However, the influx of players hasn’t included a candidate to assume the “Leo” duties this season.

The 49ers didn’t sign a player with more than nine career sacks in free agency, and they didn’t draft a legitimate “Leo” until the sixth round, Utah’s Pita Taumoepenu.

That means they will look to holdovers to assume the spot on a team that has the fifth-fewest sacks (61) in the NFL over the past two seasons. Besides Lynch, the candidates include Ahmad Brooks, Eli Harold and Arik Armstead, who, at 6-foot-7 and 292 pounds, is considerably larger than a classic Leo. Harold, a 2015 third-round pick, has three sacks in two seasons.

Lynch (14 career sacks) and Brooks (53.5) are the only 49ers with more than 12.5 career sacks.

“They want me to be a pass rusher,” Lynch said. “They want me to set the edge. They need that out of me, so I need to give that (to) them. And I need to do that for myself.”

Lynch possesses the ability, but he must prove he also has the commitment needed to succeed.

He tumbled to the fifth round of the 2014 draft because of off-the-field concerns. Moments after Lynch was selected, his strength and conditioning coach at South Florida suggested, via Twitter, that the pick proved the 49ers didn’t value integrity and character.

Three years later, Shanahan was asked last week whether Lynch was “taking the steps necessary” to improve. Shanahan implied the topic of Lynch’s work ethic had been addressed.

“There’s no doubt Aaron’s going in the right direction for us,” Shanahan said. “He came in in the offseason, we challenged him hard with just the way we worked and stuff. He hasn’t shied away from any of it. He’s jumped in on all of our stuff. … He’s gotten better each day. He’s gotten more in shape each day. And I’m seeing it on the field each day.”

Lynch wasn’t seen much on the field last year. After his suspension, he missed five games with a sprained ankle. His season totals: 1.5 sacks in seven games.

His lost season, however, didn’t inspire him to report to the offseason program near his playing weight. And that inspired this question last week: Is it fair to question his commitment?

“I know last year I probably wasn’t as committed,” Lynch said. “I mean, I was committed, but I basically (had) some off-field issues, getting suspended and getting hurt. So I don’t think my mind was in the right place as far as how the season was going. I wouldn’t say I wasn’t committed. I’m working my ass off right now. Getting down to the weight I need to get. Doing everything they want me to do.”

The 49ers want Lynch to consistently generate pass-rush pressure. At the moment, however, he probably needs to drop weight before the 49ers can gauge whether he’s their best candidate to drop quarterbacks.

“Right now, I’m in better physical shape than I was last year at this time,” Lynch said, “but I’ve still got a long ways to go.”

Eric Branch is a San Francisco Chronicle staff writer. Email: Twitter: Eric_Branch

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