It's more likely that athlete will stay too long in his or her sport than leave gracefully or early. That's why it is always shocking when a player like San Francisco 49ers linebacker Patrick Willis walks away.

Cleveland Browns running back Jim Brown retired at the age of 29 after nine years in the NFL. Detroit Lions running back Barry Sanders retired just after turning 31 and 10 seasons in the league. Minnesota Vikings running back Robert Smith retired after eight seasons in the NFL after leading the NFC in rushing in his final year at just 28.

Those three players were all running backs, and all three retired at the top of their careers. It's even more shocking to see a defensive player retire at an early age. That is what makes Willis' sudden retirement all the more shocking. After just eight years in the NFL, an injury has forced Willis to hang up his cleats.

Willis is walking away from more than $21 million in salary for the rest of his contract and more than $8 million he would have made this season. His rookie contract paid $16.7 million, and he made more than enough money to walk away from the game.

Arriving in Oxford, Miss., from Bruceton, Tenn., in 2003, Rivals.com listed Willis as a modest three-star recruit, and Scout.com gave him only two stars. Still, Willis played in all 13 games his freshman year with the Rebels.

He received All-SEC honorable mention during his sophomore season in 2004. In his junior season, the Associated Press gave Willis First Team All-SEC honors for the first time in his career, and CollegeFootballNews.com and the All-American Football Foundation gave him first team All-American honors.

Willis was showered with awards his senior season in 2006, as well, including SEC Defensive Player of the Year, first-team All-SEC, numerous all-American teams, the Jack Lambert and Dick Butkus awards, and the Conerly Trophy. Willis ended his career at Ole Miss as one of the best linebackers in the school's history.

After a spectacular college career, the San Francisco 49ers selected Willis with the 11th overall pick in the 2007 NFL Draft. Willis made an instant impact on the 49ers' defense. He started all 16 games in his rookie season.

The Associated Press named Willis its Defensive Rookie of the Year, and he led the NFL in tackles, earning First Team All-Pro honors. He was also named to the Pro Bowl in his rookie season.

Early in his career, San Francisco wasn't a good team. The team finished 5-11 in his rookie season and continued losing, finishing 7-9 in 2008, 8-8 in 2009 and 6-10 in 2010.

Even with the team's losses, Willis was one of the best players in the league, earning second team All-Pro honors in 2008 and First Team All-Pro honors in 2009 and 2010. Willis also led the NFL in tackles in 2009.

Things in San Francisco turned around when the 49ers made the playoffs and played in the NFC Championship Game from 2011 to 2013. Willis continued to rack up first team All-Pro honors in 2011 and 2012. Willis also earned Pro Bowl honors from 2007 to 2013.

He played in Super Bowl XLVII—the one where the lights went out in the Mercedes-Benz Superdome—but came up on the short end of a 34-31 loss to the Baltimore Ravens.

In 2014, Willis played in just six games before a toe injury forced him to end his season early. The linebackers' feet caused him to end his career.

"You've seen me break my hand on Sunday, have surgery on Monday, and play on Thursday with a cast on," Willis said on 49ers.com. "But there's something about these feet. And those are what made me who I am. They had you all saying, 'Wow, where'd he come from?' I know I no longer have it in these feet to go out there and give you guys that kind of 'wow.'"

Now, the biggest football question left for Willis will come in five years. After playing for just eight seasons, even spectacular ones, will the Hall of Fame voters think he did enough to earn admission?

A short list of players were as dominant at the linebacker position as Willis during his time in the NFL. Hopefully, the voters will understand that Willis was protecting his future as his feet broke down.

Willis joins Jerry Rice as the second player with Mississippi ties to help build a winning team in San Francisco. Like Rice, Willis should end up in the Hall of Fame at some point.