MIAMI — Robert Saleh slowly rotated the two rubber bracelets on his right wrist, and over the next several minutes, offered a window into his soul and the heartbeat of his players.

At a near-empty table inside a South Florida hotel ballroom this week, the San Francisco 49ers’ defensive coordinator took his time unveiling the secret behind the league’s most disruptive, destructive and dominant force this season.

“A.G.N.B.”

“A.A.”

“E.V.”

The acronyms tell the story of a talented unit that was challenged to be the best version of itself by its head coach, Kyle Shanahan. The letters also are a reminder that all-out effort and commitment — both on and off the field — are daily requirements inside the 49ers’ building. Not just the expectation on Sundays.

“These are our core principles. What we try to be,” Saleh told Yahoo Sports, as he leaned in and pointed to the first set of acronyms on his bracelets. “No. 1 is: ‘All gas, no brake.’

“On the surface level, people think about effort, but it’s more than that. We always talk about how it’s our way of life — the way you train, the way you study, the way you treat your wife, your girlfriend, your children, your friends. The way you go about your every day life. You wake up in the morning, step on the gas and don’t let go.”

View photos San Francisco 49ers defensive coordinator Robert Saleh directs players during a combined NFL training camp with the Denver Broncos Saturday, Aug. 17, 2019, at the Broncos' headquarters in Englewood, Colo. (AP Photo/David Zalubowski) More

Saleh then rotated the rubber bracelet again.

“This right here is, ‘Always attacking’ the ball,” he said. “We’re a ball-hawking defense, we’re trying to create as many takeaways and explosive plays as possible.

“And this one right here,” Saleh said, shifting the bracelet again, “is ‘Extreme Violence.’

“People think about violence and hitting people, but it’s more than that. It’s violence off the ball, it’s violence out of your break, it’s violence with your hand placement, it’s violence with your feet. As a corner, ‘Am I being violent enough with my read techniques?’”

The bracelets — one black with yellow lettering, the other a red and yellow combination — have arrived every offseason since 2017, Saleh’s first season with the team. Each year, the team orders a new shipment that is delivered to the facility right before the start of OTAs.

All of their defensive players have them. As does Shanahan.

“Sherm uses it as something to tie his hair,” Saleh said with laugh, referring to their star cornerback Richard Sherman.

Saleh had ordered a new batch of the same bracelets before the start of the 2018 season. But this past spring, he made a tweak: He had “Take It Personal” — the only phrase currently written out in full — etched into the bracelets.

“Everything in life is personal,” he said. “And if you don’t take life personal, you always shortchange yourself. So, just the mindset of taking everything personal — your effort, the way you attack the ball, the way you live your life — just take it all personal.”

That message was borne out of a particularly crushing Week 13 defeat in 2018. Shanahan seized the opportunity to make it a teachable moment in the midst of another trying season.

San Francisco flew to Seattle as the clear underdog behind an inexperienced backup quarterback and, in the end, were pushed around for four quarters. The 49ers lost 43-16.

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