The NFL isn't messing around when it comes to insisting the league's head coaches wear face masks at all times during the 2020 season.

The league already fined six head coaches — Sean McVay (Los Angeles Rams), Pete Carroll (Seattle Seahawks), Vic Fangio (Denver Broncos), Jon Gruden (Las Vegas Raiders), Sean Payton (New Orleans Saints), Kyle Shanahan (San Francisco 49ers) — for not wearing their masks during games during the first two weeks. Each coach was fined $100,000 while their respective teams were penalized to the price of $250,000.

Some folks may be wondering why the NFL is so stringent about face masks on the sidelines when the coaches are forced to undergo daily COVID-19 testing, and are required to test negative before being allowed to do their job on game day.

On Thursday, the league's chief medical expert, Dr. Allen Sills, shed some light onto the league's approach to coronavirus-related rules and regulations.

“It's part of our agreed upon protocol between the league and the NFL Players Association…” Sills explained, via Judy Battista of NFL Media. “All of the parts of that protocol are mandatory…We’ve said consistently testing is not what keeps us safe. Tests are important, but no test is perfect. We do have those false positives and false negatives, so it is possible that you could have a negative test result and still be infected. In those cases, the face coverings are very important. So we think it’s just another step that’s important in risk-mitigation.”

Sills added that certain public health authorities have requested that NFL personnel wear face coverings while at stadiums. You can see his full comments below:

After Week 1, the NFL issued a stern memo GMs, coaches, and trainers to remind them to wear masks at all times. McVay acknowledged that the warning was a response to his failure to keep his mask on during the team's win over the Dallas Cowboys.

“I figured that memo was directed at me. I’ve got to do a better job about that. So moving forward there will be a conscious effort to do that,” McVay said.