That PI in NO was a example of how he free lances too much instead of focusing on what his play assignment is. That was the second perhaps 3rd time he'd done that during the game. Like Peters was doing, he's trying to make an off scheduled splash instead of simply doing what his assignment is.
We should be glad that he did freelance, if not Lewis catches the ball and scores.
https://www.usatoday.com/story/sports/nfl/rams/2019/01/20/nfl-pass-interference-los-angeles-rams-nickell-robey-coleman/2634080002/
But even after seeing the (non)-error of his ways, Robey-Coleman was unashamed, feeling he'd taken a calculated risk and won on a play where he felt the Saints were trying to fool his defense. And to hear Robey-Coleman tell it, he probably deserves some level of credit for a season-saving play.
Robey-Coleman's assignment was to cover Alvin Kamara in the slot, but he'd noticed the 5-7, 168-pound Lewis enter the New Orleans huddle and thought he was trying to hide among his larger teammates.
"Nobody saw him but me," Robey-Coleman said of Lewis, whom he said was ducking down while trying to go unseen.
So he made a decision unconsciously formed in Rams practices, ditched Kamara before the snap and sprinted across the formation toward Lewis, uncovered on the other side of the field.
"Pure instinct," said Robey-Coleman. "McVay does that play to us every week with the quick speed break."