Super Bowl 50 is here. After two weeks of waiting, we’ll finally get to see the Denver Broncos and the Carolina Panthers take the field.  But despite all the hype, these past two weeks weren’t dominated by Cam Newton vs. Peyton Manning storylines. In fact, the majority of the headlines involved the Detroit Lions and Seattle Seahawks, two teams whose seasons have long ended.

Perhaps the biggest storyline of these past two weeks was the retirement of Lions receiver, Calvin Johnson, who reportedly told several of his close friends that he was planning on retiring and that he has played his final game in the NFL. This comes as a complete surprise. “Megatron” is coming off of his sixth straight 1000-yard receiving season and at just 30 years old, is still in the middle of his prime.

The other major headline involved Seahawks’ running back, Marshawn “Beast Mode” Lynch, who also revealed his retirement plans on Super Bowl Sunday. Lynch, like Johnson, is retiring at just 29 years old, meaning that two of the game’s iconic stars are walking away just nine years into their respective careers.

So what’s causing this recent onslaught of early retirements? One factor is money. Being two of the game’s most marketable stars, Calvin Johnson and Marshawn Lynch have made millions of dollars in endorsement deals. Additionally, both Johnson and Lynch have made a lot of money through their NFL contracts. Lynch has made an estimated $50 million through his NFL salary. Johnson has also made plenty of money in the NFL, primarily from the massive seven-year $113 million contract he signed in 2012 with the Lions.

While both players have made a lot of money throughout their careers, the dominant factor in their decisions was player safety. Johnson and Lynch have dealt with a fair share of bodily injuries throughout their careers, leaving them with chronic pain. Fear of concussions also impacted their decisions. The recent deaths of former players Ken Stabler and Tyler Sash (at only 27 years old) have scared many players, active and retired, about the potential side effects of concussions.

Johnson and Lynch weren’t the only players that have retired amid concussion concerns. Just this summer, Chris Borland, linebacker for the San Francisco 49ers, retired from the game as a 24 year old. These retirements signal that early retirement might become the norm, not the exception.