Trailing by four points with 53 seconds remaining Monday night, San Francisco 49ers coach Kyle Shanahan faced an important decision. Would he try to ignite his team's final possession with a long kickoff return? Or would he ask his offense to drive 75 yards, with one timeout, to score a potential game-winning touchdown against the New York Giants?

Shanahan's answer reflected a leaguewide trend this season under a revamped kickoff, one designed to reduce injury risk for players. Although the 49ers boast a 28-yard return average, third best in the league, returner Richie James stood on the goal line with his arms stretched horizontally in an "iron cross" formation, signaling his intent to allow the ball to fly over his head for a touchback. The 49ers' offense took over at the 25-yard line and marched as far as the Giants' 21-yard line but ultimately ran out of time in a 27-23 defeat.

Similar sequences have played out around the league as coaches and players adjust to the new kickoff rules. Touchbacks have increased and returns have decreased compared to last season; teams have trusted their offenses in a year of record-setting performances while shunning the vagaries and risks of returns. But a midseason internal league analysis, obtained by ESPN, suggests a larger and more positive conclusion: The changes are on track to save the kickoff from elimination -- an explicit threat some owners made last spring -- and could be expanded to punts in 2019.

Wedge-blocking, employed on 78 percent of kickoff returns last season, was eliminated, as was the 5-yard running start previously afforded to the coverage teams. Players were re-aligned so that only three members of the return team could be more than 15 yards from the restraining line, creating a punt-like environment of running with opponents rather than at them. And officials were instructed to rule the ball dead if it bounced in the end zone, an attempt to encourage players to stand down their blocks earlier.

In a Nov. 6 memo to a group of special-teams coaches, NFL executive vice president Troy Vincent wrote that the new kickoff rules have "successfully addressed" many of the league's concerns. The league will study final numbers in the offseason, Vincent wrote, but is already planning to reconvene the group that redesigned the kickoff to "begin discussing punt and punt return."

The memo reported that injuries on kickoffs have decreased, including zero concussions during the preseason, and noted that wedge blocks have been virtually jettisoned. Contact between blockers, meanwhile, has transferred from high-speed collisions at the back end to slower-speed interactions closer to midfield. Although there has been no final decision, it would require a significant reversal of those trends to prompt the elimination of the kickoff for next season.

"What I see is the makings of a safer play," said Baltimore Ravens special teams coordinator Jerry Rosburg, one of nine current coaches who helped design and present the new rules to league officials last spring. "I see the risks going down. We've brought the speed of the close contact down. That was my hope going into this.

"I was also hopeful that we would have a more exciting play with more return opportunities, and I wasn't correct on that. We'll see if that changes during the rest of the season. But the most important aspect is that anecdotally we have reduced the risk for the players involved."

Let's take a closer look at why the league already considers the kickoff safer in 2018 and related fallout of the kickoff rule changes.

Slower and fewer collisions

After years of concern about the kickoff, NFL owners absorbed a sobering research presentation last spring. Concussions were five times more likely to occur on kickoffs than other plays. Digging further, the data showed a strong correlation between the concussions -- as well as other injuries -- and the use of two-man wedge blocks. The injuries were occurring regardless of whether the ball was returned or if it was downed for a touchback.

Vincent handed the group of special-teams coaches an ultimatum: Figure out how to address the kickoff's injury rates or face its immediate elimination. The resulting proposal, adopted by owners in May, endeavored to minimize high-speed collisions by reducing the speed and space involved.

At the very least, the changes have produced an environment conducive to a safer play. According to the league, lower-speed blocks near the restraining line have increased 58 percent compared to 2017, while higher-speed blocks near the goal line -- the result of players running at each other -- have decreased by 43 percent.

"Those major collisions that we used to see are fewer and farther in between than they've ever been," said Minnesota Vikings special-teams coordinator Mike Priefer, another member of the coaching group that devised the changes. "The goal was to make the play safer and keep the play in the game, and that's the direction we're going, in my opinion."

Coercing players to stand down on eventual touchbacks has proved more difficult. The "iron cross" is not an official signal, unlike the arm wave of a fair catch, and some teams have used it to fool coverage teams into believing there won't be a return. If the end-of-season numbers don't show a greater reduction of injury on touchbacks, relative to returns, the league will likely look to strengthen the incentive next season, possibly by formalizing the "iron cross" signal.

Fewer returns

Coaches left little doubt about their strategy in the initial stages of the new kickoff. Through the first seven weeks, the touchback rate (64.4 percent) was notably higher than during the same span in 2017 (56.6), according to the NFL. The return rate fell at roughly the same pace, from 50.6 percent in 2017 to 33.4 percent this season.

In some cases, coaches are instructing kickers to boot the ball into the end zone rather than attempt "mortar" kicks that land short of the goal line and force a return. Kickoffs that landed in or beyond the end zone have risen slightly this season, from 68.5 percent to 71.6 percent. Special-teams coaches have to account for a delay in their coverage teams getting down field without a running start.

In other cases, returners have been told to take the touchback and an automatic spot at the 25-yard line, no matter how favorable the return might appear. This season, teams have a 36 percent scoring rate on drives that start at the 25-yard line. Even a 5-yard reduction makes a big difference. Scoring rates on drives that start at the 20 is 24 percent.

"The 25-yard line is still a pretty good motivator for a lot of teams to keep the ball in the end zone," Rosburg said. "Also, teams are still trying to figure out what the best way to return the ball is in this new situation. If there is any trepidation at all, they're going to take the ball at the 25."

Touchbacks also appeal to the risk-averse nature of many coaches. Look no further than the Week 8 game between the Los Angeles Rams and Green Bay Packers. With 2 minutes, 5 seconds remaining, then-Packers returner Ty Montgomery fumbled away a return -- after initially receiving instructions to take the touchback -- that would have set up a potential winning drive.

Priefer's Vikings have returned only 11 kickoffs this season, tied for the second fewest in the league.

"Teams like us are taking a knee," Priefer said, "because there is a better opportunity under the rules of getting the ball on the 25-yard line than fumbling or taking a chance of getting a penalty because of accidentally getting a double-team block. I know, talking to Coach [Mike] Zimmer, we're going to take a knee rather than bring it out for the most part depending on the situation because we're going to take that ball at the 25."

Rosburg of the Ravens was among those who thought returns would rise -- in both number and quality -- because cover teams would be slower to get down the field without the head start. It is true that cover men aren't getting as far downfield than they did last season. According to Rosburg, the running start can add 3 or 4 yards to a downfield position compared to those who play under the new rule, which requires players to remain at the 34-yard line until the ball is kicked.

But a corresponding personnel realignment might have washed out that advantage. Without wedge blocks, both sides are using smaller and faster players. There has been a 69 percent reduction in offensive and defensive linemen involved in the kickoff or kickoff return, making the average player involved in kickoffs about 7 pounds lighter.

Those smaller players are faster, of course. The average speed of players involved in kickoff returns on either side of the ball has increased 9 percent, to 14.3 miles per hour, according to the NFL. There has been an 8 percent increase on speeds during touchbacks, to an average of 12.6 miles per hour. They might not get down the field as quickly without the head start, but they are also more difficult to block.

"That's another reason there are more touchbacks," Priefer said. "There are faster guys covering them and there are limits to blocking them, because you need eight guys in the set-up zone. It's hard to block those guys. It's hard to sustain those blocks, because there is more speed. It's a snowball effect."

Still, those trends could shift during the second half of the season, as weather worsens and the football loses some of its natural distance. In 2016, for example, the touchback rate dropped from 60.9 percent in the first half of the season to 54.6 percent in the second.

More difficulty for onside kicks

Onside kicks are one of the primary arguments for keeping the kickoff in the game. Without them, teams attempting a comeback from a two-score deficit would have lower odds. But the new kickoff alignment rules, which require an equal number of players on either side of the kicker and prohibit pre-snap movement, have made onside kicks more difficult to pull off.

Through the first 10 weeks of the season, teams recovered only three of 31 onside kick attempts. That 9.7 percent recovery rate is less than half the rate for the 2017 season (21.1) and is well below the average that teams accumulated between 2001 and 2017 (19.7 percent).

"The good thing is there is not as many big collisions there," Priefer said. "You're not as spread out. You can't overload one side or the other. It's a little bit more spread out. Is it more difficult? I think going forward, teams are going to experiment with different types of kicks. Not the age-old high bouncer to right or left. We're going to have to challenge ourselves to have different types of kicks, maybe that can take advantage of the separation of the hands-team unit. It's going to change and evolve as well."

So what's next?

More evaluation awaits this offseason, especially if winter weather increases the number of returns during the final seven weeks of the season. But the NFL's confidence in the results thus far provides a strong clue toward the most likely direction, especially its initial plans to explore similar safety improvements for the punt.

"We can tweak what we have changed if we need to," Rich McKay, chairman of the competition committee, recently said. That's a far cry from eliminating the kickoff, an option that this season's progress appears to have rendered moot.