As mandatory minicamps across the NFL began this week, some teams used the time to emphasize a certain point to players: Don’t bet on the NFL. And if a player chooses to wager on other sports, they need to make sure they do so away from the team facility.

“We continue to hammer these things home that we’ve got to be very, very careful and understand it,” Washington Commanders head coach Ron Rivera said Tuesday. “The integrity of the league, integrity of each team ‒ and then the players’ own integrity and coaches’ integrity for that matter as well ‒ are at stake. And we have to be very, very diligent about this.”

In April, five players ‒ including four from the Detroit Lions ‒ were suspended for violating the league’s gambling policy. Calvin Ridley’s one-year ban was the first high-profile case of a related transgression since sports betting became legal in the United States five years ago. On Monday, Indianapolis Colts cornerback/returner Isaiah Rodgers revealed he was at the center of another investigation. According to reports, he made hundreds of wagers, mostly in the $25-50 range, including some bets on the Colts.

Rodgers took “full responsibility” for the situation ‒ no punishment has been handed down from the NFL, which has not yet commented on the reports ‒ and said he made mistakes.

“All I’ll say on that is an ongoing investigation with the NFL, and we are constantly educating our coaches and players about the issue,” Colts head coach Shane Steichen told reporters.

Commanders defensive end Shaka Toney was one of the three players suspended indefinitely in April for betting on NFL games. Washington reached out to the league and asked for a PowerPoint deck the team could share with its players, with senior director of player development Malcolm Blacken taking the lead. The team’s head of security, Mike Jacobs, was also involved in the presentation.

“And it is presented to them every year, but we did an extra emphasis on it,” Rivera said. “And then, I believe it’s tomorrow, the league will have a presentation as well. So we’re going to continue that. It’ll be a presentation that we will do during training camp as well.”

Tampa Bay Buccaneers head coach Todd Bowles told reporters that players always hear the message during training camp, but the team also would be sure to relay the message again this week for mandatory workouts.

“They’ll know exactly what they can and can’t do,” Bowles said.

Patriots coach Bill Belichick, to no surprise, talked about the league’s policy “in very large detail,” defensive end Deatrich Wise Jr. said, according to the Boston Globe.

“He always tells us what we need to do, what we need to stay away from,” he said. “We had a whole meeting about just that, so we do a good job of learning (from it).”

None of the players who have been investigated for violations have been in the league for more than four years, signaling that the league’s message does not always reach its younger players, who have essentially grown up with the legalization effort and access via mobile phones.

Players have to sign a waiver that acknowledges the policy, Commanders kicker Joey Slye said. In the locker room, Slye added, the rules are rarely discussed among players, with Blacken keeping them informed.

“More of the problem might be that a lot of guys aren’t reading what they’re signing,” Slye told USA TODAY Sports. “Or they’re doing what they’re not supposed to do anyways.

“If you read the stuff, you know you’re not supposed to be gambling in the facility or on team (property).”

The NFL, and all sports leagues, have leaned into gambling as another revenue source while touting “official sportsbook partners,” advertisements and more.

But rules are rules.

“Either guys are not understanding,” Slye said, “or if they did, they’re not listening.”

Follow USA TODAY Sports’ Chris Bumbaca on Twitter @BOOMbaca.

This article originally appeared on USA TODAY: NFL gambling controversy prompts teams to ‘hammer’ rules to players