Since Week 6, Mickens is allowing a quarterback passer rating of 8.3 when targeted, the best mark among rookies with 100 snaps in that span and third among all safeties.
But perhaps what has stood out the most to those around the team has been how he's been able to learn on the go after jumping right in.
"Another heady, good, smart player … it's like he's not a rookie and has been playing for three or four years. His dad played and he has been in the game for a long time," Chargers Head Coach Jim Harbaugh said. "Something great about R.J. is that he takes coaching really well. In great communication with Derwin [James] and Elijah [Molden], and he is not an error repeater.
"A mistake is made once and it's corrected and corrected quickly," Harbaugh added. "Takes to coaching and get better from it. That's a sign of a really top-notch player. He can keep building and stacking but really pleased with his game."
His ability to adjust and make plays is something he says starts during the week.
"Just making the most out of those practice reps because how you practice is how you're going to play," Mickens said. "Practicing with the same intensity whether I'm on scout team or the actual defense taking real reps, I think that was what really helps."
Mickens has made the most of his reps, whether he's on scout team or on the defense, and it's shown.
Chargers Defensive Coordinator Jesse Minter backed up what the rookie was saying, as he's been able to translate his practice reps to the game.
"Details in his game have just continued to go up and up and up… He's one of the best guys every day when it comes to finishing plays and putting himself in position," Minter said. "We don't tackle in practice, but he gets himself in position to make tackles.
"He's very detail-oriented in his preparation," Minter added. "The more and more opportunities he's gotten, the better he's played, which you hope for. Super proud of him."