Jarrett Bell says there needs to be a "sharper eye" kept on how the concussion protocol is administered from team to team. (1:43)

Concussions in the NFL dropped by 11.3 percent in 2016, according to data released by the league Thursday.

There were 244 reported concussions during practices and games in the preseason and regular season, down from 275 in 2015. But the number is still higher than it was in 2014 (206) and 2013 (229), a trend the NFL attributes in part to an increase in self-reporting by players as awareness of symptoms grows.

Concussions in regular-season games dropped by 16 to 167.

The 2016 decrease coincides with a regulatory component added to the concussion protocol prior to the season. It provides a mechanism for the NFL and NFL Players Association to enforce the protocol via investigations and possible discipline of individual instances.

"What we have to account for, too, are the additional protocols involved and the people involved in recognizing the injuries," NFL executive Jeff Miller said. "We have seen a significant culture change on those points" -- players themselves or teammates identifying what they suspect could be head injuries.

"The point of all of this ... is the effort to identify the concussions when they happen so players can get the treatment as quickly and comprehensively as they can. That is why we spend so much time on the protocols."

This week, the NFL determined that the Miami Dolphins did not fully follow the policy when quarterback Matt Moore was hit during a wild-card playoff game against the Pittsburgh Steelers. The Dolphins were not punished for failing to take Moore to the locker room for further evaluation, but they were informed that an ensuing incident would result in enhanced discipline.

Meanwhile, concussions on kickoff returns dropped by 15 percent after the league tweaked its rules to make the play safer. After moving a touchback on a kickoff from the 20-yard line to the 25, hoping to incentivize fewer returns, the NFL recorded 17 concussions on kickoff returns. There were 20 in 2015.

The rule reduced returns by 1.8 percentage points in 2016. Teams returned 39.3 percent of kickoffs during the just-completed regular season, down from 41.1 in 2015, according to ESPN Stats & Information.

However, there were more total injuries on kickoff returns in 2016. The NFL reported a total of 39 injuries attributed to concussions, ACL tears, MCL tears and hamstring strains. There were 35 such injuries in 2015.

The new touchback spot was approved as a one-year experiment and must be reevaluated by league owners this spring.

Information from The Associated Press contributed to this report.