Thanks for the link. Like many other studies of this nature there are a lot of variables to consider. In this case an in depth study into the injuries themselves could be considered. Which injuries would be attributable to the cumulative effect of the physical nature of the sport and which would not could be helpful. For example the following could occur at any point in season.
Illegal or hard hit by an opposing player...
Adverse field conditions due to weather...
Equipment failure...
Freak accident... (see Welker)
OTOH injuries like Brady's stress fracture, sports hernias and high ankle sprains would become more problematical towards the end of a lengthened season. IMO there will be more injuries, but the ratio of injured players per game will remain mostly constant. I don't care if there's 16 or 18 reg season games. The league and players will adapt to an increase like they have in the past. I just want football next year.