The NFL is a copycat league. And when one of the greatest head coaches of all time is your contemporary, you pay attention to what he's doing.
Ron Rivera's nine-year tenure with the Carolina Panthers ended last week when the team fired him following a 5-7 start.
In his latest "Football Morning in America" column, NBC Sports' Peter King shared what Rivera told him about the lessons he learned from nearly a decade as an NFL coach.
Surprise, surprise: It involves Bill Belichick and the New England Patriots.
"I've tried to pay attention to what Bill Belichick has done, and how to slowly transition guys out and transition guys into being the new core guys," Rivera told King. "That's what he's done tremendously well."
Specifically, Rivera noticed how Belichick and the Patriots have stayed current by finding players best-suited to defend modern NFL offenses featuring increasingly athletic skill players.
"Something else I just got from watching him. I don't know if a lot of people are talking about this, but the style of defensive player you need today, in my opinion, has changed," Rivera said.
"I got that based on what I saw him do last year in the playoffs. He put guys on the field that could chase (Kansas City Chiefs quarterback) Patrick Mahomes, then to stop the (Los Angeles) Rams from running.
"So looking for these big bulky defensive end-type players is no longer relevant. What you're looking for is you're looking for the Brian Burnses of the world. I just thought he did some really amazing things. You have to find the sideline-to-sideline guys who can play every down."
The Patriots had just one Pro Bowler on their 2018 defense (Stephon Gilmore) but were able to contain Mahomes in the AFC Championship Game and shut down the high-octane Rams in Super Bowl LIII with the help of versatile defenders like Patrick Chung, Kyle Van Noy and Trey Flowers.
That's in part a testament to Belichick, who's literally been coaching since the 1970s but is constantly adapting to the NFL's shifting trends.
Rivera put Belichick's lesson into practice, too: Burns, the Panthers' 16th overall pick in the 2019 NFL Draft, has 5.5 sacks this season, tied with Chase Winovich for fourth among NFL rookies.
Rivera is one of the very few coaches who's found success against Belichick -- his Panthers were 2-0 against New England during his tenure -- so we'd imagine the respect is mutual.
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Ron Rivera identifies key lesson he learned from Bill Belichick, Patriots originally appeared on NBC Sports Boston