NASHVILLE, Tenn. — Each time Marc Mariani heads out to catch a kickoff, he huddles first with the Tennessee special teams coach for a quick strategy session. Once he reaches the end zone and the ball’s in the air, the mental calculations begin.

Where will the ball come down? Short of the goal line or behind? Catch it and run? Catch and kneel? Or just let it roll out of the end zone for a touchback?

All in the seconds that it takes for the ball to fly off the kicker’s foot to the returner.

“It makes you second-guess taking it out of the end zone now, and I think that’s what the NFL wanted,” said Mariani, a 2010 Pro Bowler as a return specialist.

The NFL is halfway through its one-season experiment with a rule that places the ball at the 25-yard line instead of the 20 on touchbacks. The league wants to see how that affects returns while hoping to keep players safer by reducing runbacks. Studies have shown players are at greater risk of injury on a play that sends teams running at each other, creating relatively high-speed collisions.

Through nine weeks, touchbacks are up to 60.9 percent on kickoffs, according to Sportradar. That’s a jump from 58.8 percent a year ago and the highest rate at this point in any season over the past 11 years. Teams also are averaging just 20.5 yards per return, lowest since the start of the 2006 season.

Titans special teams coach Steve Hoffman said the rule is having the effect special teams coaches expected, making it very difficult to reach the 25 returning a kick. Teams with fast players who recognize an opponent’s coverage scheme still can attack, though the decision on when to risk returning a kick often depends on the score and time left on the clock.

“It’s hard to get it to the 25,” Hoffman said. “You ask most offensive coordinators, they’re going to call plays a lot different at their own 15 than their own 27. They don’t want to take negative plays. They don’t want to take a sack, so what everybody’s trying to do, they’re just trying to pin it.”

Through the first eight weeks, only two kicks had been returned for touchdowns – both by Philadelphia.

Then in the span of an hour in Week 9, Kenyan Drake returned a late kick 96 yards for a TD, helping Miami beat the Jets 27-23, and Colts running back Jordan Todman took the opening kickoff 99 yards for a touchdown, setting the tone for a big win at Green Bay.

Those pushed the NFL to four TDs midway through the season, matching the nine-week total in each of the previous two seasons. The league hasn’t had double-digit touchdowns off kickoff runbacks through nine weeks since 2010 – the year before the NFL moved kickoffs from the 30-yard line to the 35.

Cordarrelle Patterson of Minnesota had 10 returns of 50 yards or longer during his first three seasons with the Vikings. This season he surprised Tennessee with a 61-yard return coming out of halftime in the opener, but has had none longer than 37 yards since.

Patterson used to have the green light even backed up in his end zone, with the Vikings confident he could reach at least their 24. Now getting to the 24 means Patterson might as well have taken a knee, and Vikings special teams coordinator Mike Priefer said the rule has affected how they think.

“I think it’s going to be interesting going forward with what the league does with it as long as we keep the play in the game,” Priefer said. “It’s an exciting play. It does make a difference on field positioning. The way we teach it here is to teach our techniques to keep guys safe, keep the head out of the game, and I know a lot of coaches are doing that now. I don’t think there’s as many injuries as there has been. So we’re going in the right direction.”

The NFL still has half a season to decide whether to make the rule permanent. With the weather turning cooler, Darren Rizzi, Miami’s special teams coordinator, expects more teams to opt for the high, shorter kickoff that has been used mostly by those with both good kickers and coverage units.

“So there have been some unseen things I think have been pretty interesting, so I think that it will continue to trend downward,” Rizzi said.