Just like the Smith trade, the deal between the Chiefs and the Rams can not become official until the new league year begins March 14.
Peters steps in as the Rams' primary cornerback, which might spell the end of Trumaine Johnson's tenure with the team.
For the time being, the Rams have acquired a top-level talent with only a $1.74 million cap hit the 2018 season while the Chiefs are taking on a $1.3 million cap hit.
The other concern is how much of a contract that Johnson will command in free agency after playing the past two seasons with the Rams under the franchise tag.
The Rams entered the offseason with a desperate need at cornerback. Their No. 2 cornerback, Kayvon Webster, ruptured an Achilles tendon in December.
There's nothing concrete out there telling us exactly what Los Angeles gave up to add Peters to the mix. It also helps them sign defensive tackle Aaron Donald to an extension that is expected to eventually make him the game's highest-paid defensive player.
However, if they did go after Johnson, new defensive coordinator Matt Eberflus would be getting a big, physical corner to build the rest of the secondary around.
The news has left many scratching their head, considering that Peters is perhaps the best cornerback in the game today.
But Peters also joins the Rams with some character concerns. Per Pro Football Focus (subscription), Peters graded out as their 17th best cornerback (tied) with a +85.7 grade overall this past season.
Late in the fourth quarter of a 38-31 loss to the New York Jets, Peters was upset at a penalty and picked up the referee's flag and threw it into the stands. In at least one instance, he directed expletives at a group of fans behind the Chiefs' bench.