The 2015 NFL season was a special one for fans. Not only did the Broncos reach their second Super Bowl in three years, but they also won their first championship since Super Bowl XXXIII in 1998. However, the Broncos have suffered major setbacks this offseason. With the retirement of Peyton Manning and the departure of the Broncos’ backup quarterback, Brock Osweiler, the Broncos are currently left without a starting quarterback for the 2016 NFL season.

Peyton Manning has been flirting with retirement for several years now and many people believe he should have done so seasons ago. However, now that Manning has won his second Super Bowl, he has no reason not to retire. What better way to end a legendary career than with a championship? Besides, his mother wanted him to retire, his father said he was done in Denver, and he turns 40 on March 24th.

In addition to the retirement of Peyton Manning, other key retirements took place during this offseason. The Raiders’ Charles Woodson, who just finished his 18th season in the NFL, has retired also alongside the Seahawks’ Marshawn Lynch and the Lions’ Calvin Johnson. Woodson, who is also 39 years old, has retired with the Oakland Raiders after playing for two different teams and winning a Super Bowl with the Green Bay Packers.

Although many fans expected retirement from Woodson and Manning, two veterans, one of whom just won a Super Bowl, they were not expecting retirement from two players: Calvin Johnson and Marshawn Lynch. Both players are 30 years old and 29 years old respectively and are considered to be in the prime age for football. However, injury to both players have sidelined them for much of last season and have forced them to enter retirement.

With the retirement of four outstanding players from four different teams, the Broncos, Seahawks, Raiders, and Lions have a lot on their plate this offseason. Who will replace their star players? Only time will tell. People are already talking about 2021 though. That’s because 5 years after retirement, players are eligible for the Hall of Fame. By the looks of it, the Hall of Fame class of 2021 seems like one for the history books.