The Denver Broncos have several intense rivals.
One can look within the AFC West to find Denver's biggest rivals.
The Broncos and the Oakland Raiders have one of the most storied rivalries in NFL history. It extends all the way back to 1960 when both teams started out as AFL franchises. The two teams have met 105 times, including twice in the postseason. The Broncos won their first AFC Championship in 1977 after defeating the Raiders.
The same applies to the Kansas City Chiefs, where they started out as an AFL franchise the same year as the Broncos. The two teams have met 105 total times, but just once in the postseason—a 14-10 victory for the Broncos in the divisional round of the playoffs that led to the Broncos winning their first Super Bowl during the 1997 season.
However, this article won't focus on either of those two teams.
It will focus on the San Diego Chargers.
Of Denver's three AFC West rivals, the Broncos-Chargers have the least storied rivalry.
A lot of that can be attributed to the Chargers' lack of success after all four teams made the transition from the AFL to the NFL after the merger in 1970. From 1970-2003, the Chargers made it to the postseason just seven times.
Not only that, but unlike the Broncos' rivalries with the Raiders and the Chiefs, the Broncos and Chargers have yet to meet in the postseason a single time.
So why the Chargers?
Because they've been Denver's biggest rival over the past decade. The Chargers have been Denver's biggest thorn since San Diego clinched the AFC West title in 2004, which would lead to a run that would include five division titles from 2004-2009.
The only year the Chargers didn't win it during that time frame? 2005.
Although San Diego has fallen on hard times recently—missing the playoffs for three consecutive seasons—and have seen their win totals decrease from nine in 2010, to eight in 2011 and finally seven in 2012, the Chargers gave the Broncos the most trouble of any of Denver's rivals over the past decade.
Just what made any Broncos fan hate the Chargers even more than before over the past few years?
When the century began, it was the Broncos and the Raiders who were the two teams to beat in the AFC West.
In 2000, both the Broncos and the Raiders made it to the postseason, with Oakland winning the AFC West title that year. It would begin a run of three consecutive division titles for the Raiders before they would lose in Super Bowl XXXVII.
Since 2003, the Raiders have failed to make it back to the postseason or achieve a winning season.
The Chiefs have been a hot-and-cold team over the past 13 seasons. Kansas City has made it to the playoffs three times, with two division titles. Their best team was in 2003, when they went 13-3 and clinched the AFC's No. 2 seed.
They haven't won a playoff game since 1993.
The Raiders have been a mess for a full decade now, while the Chiefs have been mired as one of the league's worst teams since 2007—their only winning season since that year was in 2010.
Which brings us to the Chargers.
San Diego began the new millennium as the worst team in the NFL. A 1-15 record in 2000 led to the Chargers drafting running back LaDainian Tomlinson in the first round of the 2001 draft. During that same draft, the Chargers selected quarterback Drew Brees with a second-round draft selection.
Both players would play pivotal roles in rebuilding San Diego.
Two years later, the Chargers signed two-sport star Antonio Gates. Gates—along with Brees and Tomlinson—led the Chargers to their first playoff berth in nine years when they won the AFC West title in 2004. San Diego would lose in the wild-card round to the New York Jets, but the foundation of winning for a historically losing franchise was finally set.
Although Brees would eventually take his talents to New Orleans in 2006 after suffering a serious torn labrum in his throwing shoulder versus the Broncos in the final game of the 2005 season, the Chargers turned the franchise over to 2004 first-round draft pick, Philip Rivers.
This would begin Denver's biggest rivalry in recent memory—a rivalry that turned out to be one-sided for several years.
After the Broncos won the AFC West in 2005 with a 13-3 record, Denver lost in disappointing fashion to the eventual Super Bowl champion Pittsburgh Steelers in the AFC Championship Game, 34-17.
Head coach Mike Shanahan figured that the Broncos had reached their peak with Jake Plummer as quarterback. After an efficient 2005 season which saw Plummer post the second-highest quarterback rating of his career (90.2), Denver drafted quarterback Jay Cutler with their first-round draft selection in 2006.
This would begin a new era for both teams—San Diego with Rivers, the Broncos with Cutler.
Although it was known heading into 2006 that Rivers would be San Diego's quarterback, the same did not apply to Denver with Cutler. Plummer was still Denver's starting quarterback. It wouldn't be until a heartbreaking loss to San Diego on Sunday Night Football changed matters.
Although it wasn't until after Week 12, when the Broncos lost to the Chiefs 19-10 on Thursday Night Football that Plummer officially lost his starting job, it was the game four days earlier that officially put Plummer on a short leash.
Entering Week 11, the Broncos played the Chargers for first place in the West.
With the Broncos leading 24-7 in the third quarter at home, the beginning of many embarrassing collapses versus the Chargers over the following years commenced. San Diego would go on a 28-3 run in the final 20 minutes of the game to defeat the Broncos 35-27.
This loss—combined with the following week's loss to Kansas City—ended the Plummer era and began the Cutler era.
Denver would never regain first place in the division for the remainder of the season, as San Diego would go on to clinch the No. 1 seed in the AFC.
Denver would lose their next three games—including a 48-20 loss to the Chargers at Qualcomm Stadium in Week 14—before finally winning again in Week 15.
The Broncos would miss the playoffs after going 2-3 with Cutler as the starting quarterback and a devastating loss to the lowly Niners in Week 17.
To put into perspective what Denver's loss to San Diego in Week 11 meant, the Broncos went 2-9 versus the Chargers from 2006-2011 before the Tim Tebow era began.
The most painful loss during that period?
Week 17 of the 2008 season.
Let's recap this 2008 season as short as possible—the Broncos led the division from Week 1 until before the end of Week 17.
Entering Week 15, the Broncos were 8-5, while the Chargers were 5-8. Denver had three games to win just one game, and they would have clinched the division.
Instead, one of the most monumental collapses in NFL history took place.
Denver would lose their next two games, while the Chargers would win their next two games.
This would set up a national television finale on Sunday Night Football that would see the 8-7 Broncos play the 7-8 Chargers at Qualcomm Stadium for all of the marbles—a playoff berth and the division title.
It was never a contest.
San Diego entered halftime with a 24-6 lead before putting the Broncos out of their misery with a 52-21 victory.
The victory marked the first time in NFL history that a team with a three-game lead entering the final three weeks of the season lost all three games and missed the postseason in the process.
Other than humiliation, what was the aftermath of the loss?
The firing of head coach Mike Shanahan.
The man who brought Denver's first and only two Super Bowl trophies to Mile High, fired after an unceremonious collapse.
When asking most Broncos fans, they'll tell you their most hated rival is the Raiders. Some may say the Chiefs.
Rarely do any Broncos fans say the Chargers.
And although it's true the Broncos-Chargers rivalry lacks the old-school hatred of Denver's other two rivalries, one thing remains certain—no team caused more pain in recent memory to the Broncos for a six-year window than the San Diego Chargers.
These losses led to successful quarterbacks and head coaches losing their jobs.
These defeats led to San Diego stealing away division titles from the Broncos.
That is why every Broncos fan should hate the Chargers.