By Neel Ramachandran on April 8, 2016

Buffalo Bills linebacker and former Cardinal standout A.J. Tarpley announced his retirement from the NFL on Wednesday, citing health concerns after receiving the third and fourth concussions of his career during the 2015 season.

“I’m walking away from the game I love to preserve my future health,” he wrote in a post on his Instagram account. “This decision is the hardest I’ve made yet but after much research and contemplation I believe it’s what is best for me going forward.”

The Minnesota native was signed as an undrafted free agent by the Bills last year and saw playing time almost exclusively on special teams before being waived from the team mid-season. He returned to the team in December after injuries at the linebacker position.

Tarpley shined after his return, earning a starting role in the penultimate game of the season against the Dallas Cowboys and recording both a forced fumble and an interception to fuel the Bills to a victory.

In the last game of the season, Tarpley intercepted Jets quarterback Ryan Fitzpatrick in the waning seconds of the fourth quarter to seal the win for the Bills. The play would be the last of his career.

Prior to his professional stint with the Bills, Tarpley was a member of a vaunted Cardinal linebacker corps that included the likes of Trent Murphy, Shayne Skov and Chase Thomas. In 2014, he captained a Cardinal defense that was top-5 nationally in points per game and total defense, ranking second on the team in total tackles and garnering an All-Pac-12 Second Team recognition in the process.

During his five years on The Farm, Tarpley reached four straight BCS titles and won back-to-back Pac-12 Championships, helping to elevate the Cardinal from a mediocre program to contenders on a national stage. His collegiate career, however, might be best remembered for his 2011 performance against USC. Tarpley recorded an interception and a fumble recovery that secured a 56-48 triple-overtime victory for Stanford, in what is widely considered one of the great college football games in recent memory.

At age 23, Tarpley joins a number of high-profile NFL young athletes, including 49ers Chris Borland (24) and Anthony Davis (25), that have announced their retirement preemptively due to health and concussion concerns.

Contact Neel Ramachandran at neelr ‘at’ stanford.edu.