Inside Slant: The NFL's ACL numbers

The NFL revealed Thursday that players reported 13 percent fewer concussions during the 2013 regular season, and that statistic rightfully produced the headline from a presentation by the members of the league's health and safety division. The league also released its official count of ACL injuries, a topic we've discussed a number of times this season, and those figures merit a closer look.

The chart provides a snapshot of the league's tally, which it said was culled from the medical staffs of each team. It puts the count of ACL tears during the preseason and regular season (games and practices) at 57, which was actually lower than the total over the same period in 2012.

By my research, working off a list originally compiled and distributed via Twitter by @ACLrecoveryCLUB, at least 62 players tore their ACLs between the start of offseason work and last Sunday's championship game. The NFL's time period appears to have begun with training camp and ended with Week 17 of the regular season.

It's reasonable to assume the league's 2011 and 2012 numbers would have grown over that larger time span as well. So based on these updated numbers, we can't conclude that 2013 was a record-breaking year for ACL tears despite anecdotal fears to the contrary.

In releasing this information, the NFL had a vested interest in debunking two theories that link its actions and decisions to an increase in injuries.

The first is that new rules regarding hits to the head would inspire more low hits and produce more knee trauma. As we've discussed several times, that did not occur except in a handful of highly visible instances. (See: Miami Dolphins tight end Dustin Keller and New England Patriots tight end Rob Gronkowski.)

The second suggests that the 2011 collective bargaining agreement's restrictions on offseason training opportunities leaves players more vulnerable to ligament injuries when football activities resume in the spring and summer. That theory has not appeared to manifest itself in ACL injuries over the past three years, although I don't have figures for 2010 or earlier for comparison.

Patriots coach Bill Belichick went on record last month linking the shortened offseason to what he believes is an increase in all kinds of injuries. What we do know is that more players were placed on injured reserve (125) in 2013, through the championship games, because of knee injuries than in 2012 (121) or 2011 (93), based on ESPN Stats & Information research.

While I agree the data doesn't support the first theory, I think the second requires further evaluation and discussion.

So what have we learned in our first year of attempting to track ACL injuries? There was without question some intense pockets of instances, peaking around Week 7, and the high-profile names of those ultimately affected -- Reggie Wayne, Sam Bradford, Tyrann Mathieu, Geno Atkins -- added some weight to the topic. But the rate dropped over the second half of the season, approaching the league's recent high but ultimately falling short.

Does that mean there is nothing to see here? I wouldn't say that. Discussions this year about shoe selection, playing surfaces and other potential contributing factors had merit. There is no reason to wait until a record is set before initiating the conversation.