Mathis, who announced his retirement Tuesday after 13 seasons, was the mentor in the secondary for the Lions and someone whom others looked up to, even beyond his position group.
He led with advice and demeanor, which was something he started from his early days with Detroit in 2013 by working with then-rookie cornerback Darius Slay. He helped teach Slay how to be a professional, forming a strong bond between the two.
To Slay, Mathis was a big brother.
I'm go miss my big brother words can't describe the love I have for u big homie. Retirement of the great R.Mathis✊🏽 pic.twitter.com/cwe4l1KIyg— Darius slay (@_bigplayslay23) February 16, 2016
Mathis was able to influence because his play on the field backed up his words. He was a Pro Bowler in 2006 and played in 175 career games -- 137 in Jacksonville and 38 in Detroit. He had 32 interceptions, returning four of them for touchdowns. And he was a strong, fundamental player who continuously tried to learn.
Mathis was one of the more thoughtful and most respected players in the Lions' locker room. He had opinions on a multitude of topics and was never afraid to voice them, including about what the NFL needs to do about concussions and brain injuries. He went as far as to tell me earlier this season he plans on donating his brain to research after his death.
He also wants to steer his son away from football at least until high school.
Mathis was one of the easiest players in the locker room to chat with. He was respectful, listened to differing opinions and took time to get to know essentially everyone in there, from club personnel to the media. He was engaging and honest with how he saw things.
That included his own future.
While it was never clear that he was going to come back for the 2016 season -- he left that up in the air from the second he was placed on injured reserve with a concussion in Week 10 -- his loss will leave a void in Detroit’s locker room and on the field.
The Lions likely will have to look to safety Glover Quin, already one of Detroit’s best players and vocal leaders, to be even more of an influence. Detroit will have to search for more veteran depth in the secondary and perhaps a starter, as the Lions would have Slay and Nevin Lawson as the team’s starting cornerbacks if the season started today.
They’ll also have to find someone to keep mentoring the young cornerbacks as they come into the league.
Mathis' presence with the Lions will be missed by his teammates as he heads off to his next career, likely somewhere on a golf course.
After all, he joked last offseason that after he was done with the NFL, he wanted to make a run at a pro golf career. That can, in theory, start Tuesday.