ESPN.com first reported the trade, which will not become official until the start of the new league year on March 14. It's the second major trade involving the Chiefs that will occur that day following the deal that will send quarterback Alex Smith to the Washington Redskins.
The Chiefs have been aggressively seeking to trade Peters, an All-Pro during the 2016 season, as part of both a youth movement and shift in locker room culture.
The 25-year-old Peters emerged as one of the NFL's best cover cornerbacks, picking off at least five passes each of his first season in the league. But he also carries significant character concerns, beginning with getting thrown off his college team at Washington after a run-in with his coaches.
Peters has drawn the ire of some fans for refusing to stand for the national anthem, even though he has never explained why he is protesting. He's been involved in shouting matches with assistant coaches on the sideline, bizarre and sometimes divisive locker room antics, and was even suspended for a game last season after tossing an officials' penalty flag into the stands.
Peters thought he was ejected after that incident against the New York Jets and left the field, only to run back out - not wearing socks - when he realized he was not disqualified.
None of those character concerns was evidently enough to dissuade the Rams from making a deal, though. They were desperate for a shutdown cornerback for defensive coordinator Wade Phillips, especially with Trumaine Johnson due to hit free agency after spending two seasons playing on the franchise tag.
The Rams' slot cornerback, Nickell Robey-Coleman, also is expected to hit free agency, and No. 2 cornerback Kayvon Webster will be trying to return from a ruptured Achilles tendon sustained in December.
Peters will count $1.74 million toward the salary cap this season, the final year of his rookie deal, and the Rams will have until May 3 to decide whether to pick up his fifth-year option.
The Chiefs will obtain a potential replacement for Peters when the Smith deal becomes official. As part of their pending trade with the Redskins, the Chiefs will receive coveted cornerback Kendall Fuller, who many believe is on the verge of stardom, along with a third-round draft pick.
Prior to the trades, the Chiefs were only scheduled to have four picks in the upcoming draft, which would have significantly hampered new general manager Brett Veach's chances of upgrading the roster.
They were granted a sixth-round compensatory pick Friday for allowing quarterback Nick Foles to sign with the Philadelphia Eagles last offseason, and are expected to get additional choices from the Rams. But it's unknown whether those will occur in April's draft or in following years.
The Rams are already without a second-round after their trade for Sammy Watkins last year.
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