SAN DIEGO -- A season's worth of bushy brown hair hangs uncomfortably from Eric Weddle's face, making it hard for him to buckle his chin strap on game days.

Weddle's beard serves as the inspiration for his Twitter handle -- @weddlesbeard, what else? -- emerging as somewhat of a symbol for the San Diego Chargers' improbable playoff run. Weddle says he won't shave it off until his team reaches the Super Bowl, or is eliminated from the postseason.

He received the epiphany of growing a beard after seeing an old picture of his father, Steven Weddle, fishing in Cabo San Lucas, Mexico, similar to this photo he posted on Twitter.

“I wondered if I could grow one because I never had one in my life,” he said. “It's a part of me now. I like it. It's cool."

Weddle also had his hair cut into a Mohawk at the start of this season as promise to his son, Gaige, who also shaved his head into a Mohawk.

But bushy beards and unique haircuts do not define Weddle the football player. His play does. The 29-year-old is one of the most versatile safeties in the game, the glue that holds together San Diego's much improved defense together.

“We've been the underdog all year,” Weddle said. “I've been the underdog my whole life. It's no different. We're out to continue to believe in ourselves. The great thing about this team is the struggles, and the ups and downs have really molded us into what we are right now, which is a confident belief in one another.”

The Chargers can thank this year's second-half run for the improvements made on defense, specifically the secondary.

San Diego allowed 23 passing touchdowns during the regular season, No. 12 in the league. But just five of those came in the team's final five games.

The Chargers forced 12 turnovers, including seven interceptions in the past six games, helping the defense hold teams to 16 points a contest. Also, the Chargers are holding teams to 35 percent on third downs during that stretch, consistently giving the ball back to an offense that leads the league in time of possession.

The return of linebackers Donald Butler, Jarret Johnson and Melvin Ingram from injuries helped improve the talent level and overall play on defense.

But at the heart of San Diego's turnaround has been the steady play of Weddle.

“How he plays the game and how he approaches it has been the key to a lot of our success,” Chargers defensive coordinator John Pagano said. “He keeps getting better each week. He's a gamer, and that's what we need from him.”

“He's a football player,” added Pagano. “He's the other coordinator on the field that leads and get people lined up.”

Weddle earned his second invitation to the Pro Bowl this season, leading San Diego in tackles during the regular season with 115. He's also been a first or second-team All-Pro selection the last four years -- the only player at his position who can say that.

“He's a great player,” Chargers cornerback Shareece Wright said. “He's a great leader. He's always keeping us on top of our game, and always helping us out. He's like a quarterback back there.”

Weddle has 18 interceptions and six sacks over his seven-year career. And at 5-11 and 200 pounds, don't sleep on his speed.

“People underestimate how athletic this guy is,” Chargers secondary coach Ron Milus said. “He is a tremendous athlete -- quick, fast. He's able to hit, so I think people underestimate his athletic ability, and how good the kid is.

“If need be, he can play corner. So he can play anything other than defensive line. He's smart enough to handle all of that stuff. He's probably the brightest guy on our defense, knowing exactly what everyone has to do at all times.”

Weddle might not make the highlight reel hit across the middle, but he is a sure tackler. Perhaps Weddle's greatest strengths are his overall understanding of the game and ability to play with anticipation, which sometimes allows the San Diego safety to be in place to make a big play before the ball is snapped.

While he may go under the radar nationally playing in a sleepy town like San Diego without much media attention, Weddle believes he's one of the best at his position.

“I think I have respect from players, coaches and certain media who watch the games,” Weddle said. “I'm not a youngster anymore. I don't really worry or waste my energy on where I rank and this and that. I know where I'm at. I think I'm one of the best. If you don't think that, then that's your opinion.

“I know what I bring to this team in what roles I do. And I feel like when you look at me and what I can do, there's not many guys who can do that.”

Weddle will face one of the toughest challenges in his career in trying to get the best of Denver quarterback Peyton Manning in Sunday's AFC divisional playoff matchup. But Weddle can look to his past experiences for more inspiration.

Weddle has three career interceptions against Manning, two of which have been returned for touchdowns.

“It's difficult no matter what, no matter how many times you're playing him,” Weddle said about playing against Manning. “He's so good at the line of scrimmage. He very rarely makes mistakes, or forces the ball into areas. You could be in position all game, and never really get the ball thrown at you. And the one time you're not, he'll find you and it will hurt you.

“It's very stressful. Play by play you really have to take that role that, this could be the difference of winning or losing on every play against him, because that's how good he is. He can kill you if you're not in the right position.”