THOUSAND OAKS, Calif. -- Lamarcus Joyner didn't understand it. He excelled as a safety in college but couldn't play there in the pros. Three years of his NFL career went by and Joyner was being used exclusively as a slot corner by the Los Angeles Rams, which meant he typically played in only about two-thirds of the defensive snaps.

"To me, it was like having a million-dollar check you can't cash because the bank just don't want to accept it," Joyner said. "It's not that it's not legitimate; they just don't want to accept the check."

That all changed with the new coaching staff. The Rams opted against bringing back longtime safety T.J. McDonald -- who wound up being suspended for the season's first eight games -- because they believed Joyner needed to be on the field at all times.

It didn't take long, either.

"We came in, we watched the film from the year before and we said, 'This guy's one of our best players and he only played half the time -- what should we do?'" Rams defensive coordinator Wade Phillips recalled. "We said, 'Well, let's play him all the time then.' It sounds simple, but he's too good a player not to be on the field, in my opinion. And he thought the same way. I saw 'Hard Knocks.' I think he felt the same way."

Yeah ... that.

HBO's "Hard Knocks" followed the Rams through training camp last year. And one of the more memorable episodes included Joyner being so upset about his limited role that he decided not to show up for practice one morning. It took a heart-to-heart from former coach Jeff Fisher to persuade him to even stay with the team.

Phillips teases Joyner constantly about that.

"I didn't mind it being out," Joyner said. "You had people saying, 'Why's this guy complaining?' Everybody from the outside looking in thought that the grass was green on the other side. And once that got out, I wanted everybody to know my frustration."

Rams safety Lamarcus Joyner has three interceptions this season, including one he returned 46 yards against the Cardinals on Dec. 3. Christian Petersen/Getty Images

In his expanded role, Joyner has been the Rams' most valuable defensive player outside of Aaron Donald.

Joyner, who still sees occasional time at slot corner in subpackages, is currently the NFL's fourth-highest-graded safety by Pro Football Focus, behind only the Minnesota Vikings' Harrison Smith, the Chicago Bears' Adrian Amos and the Tennessee Titans' Kevin Byard. He has three interceptions, one of which he returned for a touchdown, and nine passes defended. And that doesn't even begin to explain his value.

Joyner has been targeted 25 times and has allowed only 11 receptions, allowing a 32.5 passer rating that ranks fourth among safeties who have played at least 460 snaps, according to Pro Football Focus. His coverage grade, 92.7, ranks first among the 88 players who qualify.

"He doesn't have great size," Phillips said, "but he makes plays all over the field."

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Joyner is listed at only 5-foot-8, but he has great length and surprising strength.

"He's a great athlete," Rams coach Sean McVay said, "but then he's also fearless."

It's evident mostly with this stat: Joyner has yet to miss a single tackle this year. Only two other safeties, the New England Patriots' Duron Harmon and the Arizona Cardinals' Tyvon Branch, can claim the same.

"I tell people all the time -- you can coach technique, you can coach fundamentals," Joyner said. "The one thing about tackling is attitude, where your heart is at. Tackling is all heart and attitude."

Joyner played safety as a sophomore and as a junior at Florida State. But he was moved to slot corner for his senior year in 2013, because NFL teams questioned his coverage ability and scouts believed he would be better served in a tighter space. Joyner still bristles at that. He'll tell you his transition to NFL slot corner as a rookie in 2014 was a lot more difficult than his transition to NFL safety as a fourth-year player in 2017.

"It’s something I’ve been doing all my life, in little league, high school, college -- I was an All-American safety in college," Joyner said. "I wanted to show the league that I can cover and can do both -- I can play slot corner; I can play safety. And unfortunately, no one gave me the benefit of the doubt that I can play safety in this league."

Phillips did, and now the Rams are reaping the benefits.

So is Joyner, who is on the last year of his rookie contract and has seen his value increase significantly this season.

"I just felt like I had a talent that I wasn’t given an opportunity to present in this league," Joyner said. "And it was very frustrating. One year is enough, but three years? I just put my faith in the lord, knowing that someday it would come and I was going to get an opportunity."