Sure did not take long for some significant injuries at NFL training camps - Philadelphia Eagles receiver Jeremy Maclin, Baltimore Ravens tight end Dennis Pitta, Denver Broncos centre Dan Koppen, to name only three.
Immediately, some theories developed: Too much off-season work. Not enough. New labour-contract rules limiting padded practices to one per day, while generally seen as helpful, are hardly a cure-all.
Washington Redskins linebacker London Fletcher thinks some guys get hurt in camp because players are trying so hard to impress coaches and earn a roster spot or a starting job.
"You know now coaches are really evaluating you," said Fletcher, whose teammate, second-year linebacker Keenan Robinson, tore his left pectoral muscle on day one of training camp. "You've got guys with a competitive spirit and they're looking at it, like, 'My job's on the line. I need to make a play' and not realising there's going to be times to show the coaches that you can hit, you can make plays in preseason games, but you don't want to have a guy go down because of something that happened in practice."
Whatever the cause, severe injuries are increasing in the NFL lately. The number of injuries that forced a player to miss at least eight days jumped every year from 2009 to last year, according to an analysis of NFL injury data. The Edgeworth Economics study, based on information collected by the league, also shows that players with concussions missed an average of 16 days last season, up from only four days in 2005, while the length of time out for other types of injuries has been steadier.
"Severe injuries are increasing in frequency," Jesse David, the economist overseeing the study, said. "I know that's a very important issue for both the players' association and the league - trying to tweak the rules and the equipment to deal with that. But despite everything they've been doing, it's still going on."
The study says there were 1,095 instances of injuries sidelining a player for eight or more days in 2009 - including practices and games in the preseason, regular season and postseason - and that climbed to 1,272 in 2010, 1,380 in 2011, and 1,496 in 2012. That is an increase of 37 per cent.
Concussions have become a far-more-noticed part of football in recent years, with more talks on the links between head injuries and brain disease, hundreds of lawsuits brought by former players, and NFL rule changes to try to better protect players.
In the nine years examined in David's study, the average number of days missed due to head injuries by league players went from 4.8 in 2004, four in 2005, and 4.1 in 2006, to 10.9 in 2010, 12 in 2011, and 16 last season.
NFL spokesman Brian McCarthy, who said the league would look at the study's findings, attributed the longer absences for players with concussions to more caution in the treatment of those types of injuries.
"We do know that the game is safer now, but we still have work to do. We continue to work hard on many fronts to make the game better and safer," he said.