John Urschel is retiring from the NFL after three seasons.

“This morning John Urschel informed me of his decision to retire from football,” John Harbaugh said in a statement. “We respect John and respect his decision. We appreciate his efforts over the past three years and wish him all the best in his future endeavors.”

Urschel is currently a Ph.D. candidate in mathematics at Massachusetts Institute of Technology (MIT).

In an article written for the Players’ Tribune in 2015, entitled “Why I Still Play Football,” Urschel starts the piece by saying “I envy Chris Borland.” Borland retired at 24 years old due to concerns about long-term brain injury.

A fifth-round pick in 2014 out of Penn State, Urschel has suited up at guard and center for 42 games and started 15, including two playoff games in 2014.