ALLEN PARK, Mich. -- When Rashean Mathis signed with the Detroit Lions last season, he was looking for a job and a way to extend a career he believed had been cut somewhat short in Jacksonville, the only place he had played in the NFL.

When he arrived in Detroit, though, he ended up becoming so much more.

By the third game of last season, Mathis was in the starting lineup for the Lions. By the end of the year, he was the team’s top cornerback and had proved to himself he was still healthy enough and good enough to play in the NFL.

It took a little while in the offseason, but eventually Mathis returned to Detroit under new coach Jim Caldwell, where he remained a starter in the defensive backfield and also continued his almost equally-important role as mentor.

“He was one of those guys that every week you played against him, you had to know where he was because he was very, very good in his craft,” Caldwell said. “He’d intercept the ball and create problems for you in the run game. Along with length, as well as intelligence, he was a tough guy to deal with and I’ve come to appreciate him even more, now that I’m on the same team.

“He’s smart, a consummate professional in every single facet. He works hard, he studies, he teaches the young guys, sets a great pace for them, he’s always up for practice and meetings, he’s a first class competitor. I mean you name it, this guy is a quality individual.”

That has never been in question with Mathis, who spent last season tutoring then-rookie Darius Slay, whose job Mathis had taken. That could have been an acrimonious situation, except Mathis had become such a mentor for Slay early on that it eliminated any possible tension between the old veteran and the young rookie.

Now, they are the Lions’ two starting cornerbacks, having to work together to make sure Detroit doesn’t allow big plays this season.