Marcus Peters still believes in Marcus Peters. Do the Rams?

McFarland says key to Rams-Chiefs will be the run game (0:33)

Booger McFarland previews Monday's matchup between the Rams and Chiefs and how the run game will be a major factor in the outcome. (0:33)

THOUSAND OAKS, Calif. -- At least this time it wasn't the official's flag, like the one he threw last season, that he chucked into the stands at MetLife Stadium.

Marcus Peters was looking to break out of a slump. Nine weeks had passed since the Los Angeles Rams cornerback intercepted a pass.

And Sunday against the Seattle Seahawks, Peters saw a chance to make it happen. Or so he thought.

Peters pressured Doug Baldwin as the Seahawks receiver burst off the line, but he held onto Baldwin just a little too long, before he turned and picked off a haphazard pass from Russell Wilson. An official threw a flag, and Peters appeared bewildered that he'd drawn a penalty.

Before the referee announced the ruling, Peters threw the football into the stands at the Los Angeles Memorial Coliseum, then turned to the field and readied himself for the next play.

This season, Peters hasn't been under any false impressions. The fourth-year pro knows he's been getting beaten too much, and he'll be the first to tell you. But Peters, who has a league-high 20 interceptions since 2015, said he's still "a top f---ing corner in the league."

The question is, as the Rams (9-1) prepare for a Monday night showdown (8:15 p.m. ET, ESPN) against Peters' former team -- the Kansas City Chiefs (9-1) -- what has to happen for the two-time Pro Bowl cornerback to play like it?

The Rams caught the attention of the NFL in the offseason when they traded for Peters, giving a fourth-round pick this year and a second-round pick in 2019 to the Chiefs. They were serious about upgrading their defense, and intent on making a Super Bowl run.

The Chiefs, perhaps, had a message of their own: Peters, for all his talent and playmaking ability, wasn't worth the headache before and after the whistle.

In Kansas City, chairman Clark Hunt was upset about Peters' protests during the national anthem. The two eventually compromised around midseason, and from that point Peters stayed in the locker room until the anthem was finished.

More publicly, a camera caught Peters directing an expletive at a fan behind the Chiefs' bench. And later in the season, things got downright bizarre. In a game against the New York Jets, Peters was penalized after throwing an official's flag into the stands. Peters then retreated to the locker room even though he had not been ejected from the game, and later returned, not wearing his game socks.

When Peters arrived in L.A., he addressed a reputation that preceded him, and has not looked back.

Coaches and teammates have welcomed Peters for who he is, brutal honesty and all, no matter the time or setting. And unlike in Kansas City, Peters has kept the scenes to a minimum.

There was the ode to Marshawn Lynch in Oakland -- when Peters leaped backward and grabbed his crotch as he returned an interception for a touchdown. The gesture earned him a $13,000 fine.

And, from his "s---, pay the man" analysis of Aaron Donald's contract dispute to the in-depth description of his "f--- it syndrome," there has been the occasional curse-laden, viral-sensation media sessions.

Most recently, Peters was asked about Sean Payton's comments that the New Orleans Saints coach got the matchup he wanted on a 72-yard touchdown pass to Michael Thomas, on which Peters was the defender.

"Tell Sean Payton to keep talking that s---. We going to see him soon, you feel me?" Peters said. "Because I like what he was saying on the sidelines, too. So tell him to keep talking that s---. I hope he see me soon, you feel me? Then we going to have a good lil, nice lil bowl of gumbo together."

While the Chiefs had their fill of Peters, the Rams have not wavered publicly in their support.

Peters, to his credit, has boldly accepted one of head coach Sean McVay's biggest tenets: accountability. And his "get beat, move on" message has resounded through the organization, even if Peters’ delivery and personality haven't always jibed with the Rams’ buttoned-up, football-first public persona.

"He isn't in the business of fluff," cornerback Nickell Robey-Coleman said.

Peters, 25, made his name with the Chiefs playing mostly off-man coverage in a scheme that allowed the 6-foot, 195-pound corner to rely on his instincts, ability to diagnose the quarterback and ball skills. In a word: freelancing. In three seasons, Peters was named the NFL's Defensive Rookie of the Year, earned first-team All-Pro honors and forced 24 turnovers, including a league-high 19 interceptions and five forced fumbles.

With the Rams, he has struggled to adjust to defensive coordinator Wade Phillips' 3-4 scheme designed for the corners to often play press coverage at the line of scrimmage. Peters' eyes too often have fixated on the quarterback, and too often his receiver has taken advantage. It also hasn't helped that veteran Aqib Talib, who starred in Phillips' scheme when the Denver Broncos won the Super Bowl, has been on injured reserve since Week 4.

But Phillips said the Saints breakdown was his fault. There was Peters standing across from Thomas -- who was on pace for a record day -- as free safety Lamarcus Joyner crept closer to the box. Peters looked to his left, hollered at teammates and waved his arm. Before he knew it, Thomas sprinted past him.

Peters -- about four yards off Thomas -- jumped in a desperate attempt to break up the play, but with no safety help deep, Thomas took it in for a touchdown, busted out a cell phone and delivered a final dagger in the Rams' first loss of the season.

"I'm putting that on me," Phillips said. "Any time that it's third-and-7, it's the end of the game and you've got one-on-one with no help with their best player, then that's on the coaches."

It also proved to be a career day for Thomas, who caught 12 passes for a franchise-record 211 receiving yards. According to NFL Next Gen Stats, Peters was the nearest defender on eight of Thomas' targets; he caught six of them for 127 yards and a touchdown.

"Regardless of what Coach called, we've got to go out there and make plays," Peters said. "And we just didn't -- I didn't execute."

Peters was also beaten deep for scores in games against the Chargers, Vikings, Packers and in the first meeting with the Seahawks.

Peters has been the nearest defender on seven touchdown passes, the most given up by a cornerback this season, according to NFL Next Gen Stats. His lone interception came in Week 1 against the Oakland Raiders, and his touchdown-to-interception ratio sits at 7-1 this season, compared with 4-3 in 2017. And targeted receivers are averaging 11.5 yards per target against him, the fifth-highest rate allowed by a cornerback with at least 25 such targets.

"In a lot of instances he's isolated one-on-one with the other team's best receiver and that's come up throughout various times this season," McVay said. "There's going to be an element of, those great players will make some of their plays. I think the standards that Marcus has for himself, that we have for him, we expect him to play and make some of those plays."

Despite a lack of results, Rams coaches have maintained their confidence in Peters' ability to thrive in their system. Peters realizes he hasn't lived up to the reputation he built with the Chiefs, and that his performance for the rest of the season will go a long way in determining his future.

"When you perform in this league as much as I did, and you come in and you are one of these players who makes those plays, and used to making those plays, and those plays not coming, it kind of frustrates you," Peters said. "But when you've got an offense and defense as talented as this is, it's just all about finding your groove and finding where you fit in through everything."

This offseason, a decision likely will need to be made about Peters' future. He is in the fourth year of his five-year rookie deal, and is scheduled to make $1.74 million this season and $9.06 million next.

But beyond 2019? The Rams don't have a recent history of giving long-term deals to defensive backs. Janoris Jenkins departed in free agency to sign with the New York Giants, and Trumaine Johnson signed with the Jets.

Peters doesn't want to leave L.A. He’s happy with the coaching staff, the culture and environment with his teammates. But the question remains: Can he produce enough over the final six games and playoffs to keep the Rams happy and prove he's worth a long-term extension?

Peters hasn't addressed any contract talk, choosing to focus on the immediate future and playing to his standard.

After Sunday's victory, Peters posted a photo of himself on Twitter, clad in the Rams' yellow-and-blue throwback jersey, a smile plastered across his face.

"Back on track," Peters wrote.

For Peters, Monday night is another opportunity to show the Chiefs what they gave away, and a stage to prove to the Rams that they made the right decision.

"With me, I'm going to continue to fight," Peters said. "That's the type of player I am. Who gives a s---, you're going to get beat in football. But you go out there, you compete to the highest of your ability, and s--- happens."

ESPN's Adam Teicher contributed to this report.