One reason football is seeing more head-to-head contact on tackles is that football fundamentals have changed over the years, players and coaches say.
Jamal Anderson, a former All-Pro running back with the Atlanta Falcons, said NFL players have changed even since he entered the league in 1994.
"These guys are bigger, they're much stronger and much faster," he said Wednesday during an interview on CNN International.
And those big, fast players don't tackle with their arms they way players used to, he said.
"Fundamentally, this is one thing that's missed out with all the big hits and the clips that you see, is fundamental blocking and tackling in football," Anderson said. "It's just nonexistent."
"You see players leaving their feet to make tackles, you see guys sticking their forearms out in their shoulder pads," Anderson said. "That's the thing the NFL is trying to guard against. You don't want to have these guys who are bigger, stronger, faster than they have ever been at any point leading with forearms to other guys' necks, sticking their head down, to think that's the right way to make a tackle."
Jon Gruden, a former college and NFL coach, agreed that players aren't learning fundamental skills.
"I think you're a better tackling team when you gang tackle," Gruden said Wednesday morning on ESPN Radio's "Mike and Mike" show. "When you see guys in these one-on-one situations, (the tackling is) maybe not as good as it was in the past."
Unless the NFL steps in and puts a halt to the practice through yardage penalties, fines and suspensions, the problem will continue, Anderson said.
"What you're essentially doing is teaching not only the guys in the league that are going to come, it's high schoolers, it's college players. Everybody is watching the NFL," he said.
The offensive players who most often are the recipients of vicious hits could protect themselves better too, Gruden noted on ESPN Radio. Receivers running patterns across the middle of the field need to get out of the way if the ball is not coming to them and take a low posture after making a catch, he said.
Nevertheless, there's no excuse for a missile attack by a defender, he said.
"When you see a guy leave his feet and spear a guy with the crown of his helmet, I think suspension is in order for those hits," he said on "Mike and Mike."
Football players' brains show lasting effects from repeated traumatic blows, said Chris Nowinski, a former college player, professional wrestler and author of the book "Head Games: Football's Concussion Crisis."
"These are the kind of athletes that would run through a brick wall for you," he said Wednesday on CNN International. "But the reality is we can't have ex-NFL players all coming down with dementia because we thought it was fun to see them knocked out, because it made us want to cheer a little louder. That's just not a reality that we can accept.
"If we're going allow kids to play the exact same way that NFL players play, then we can't allow these kinds of hits."
Football is a physical game, and players and fans enjoy hard hitting, Anderson said.
"When you watch the teams that you support, you want to see them make big hits," he said. "You don't want guys to get hurt. You don't want permanent injuries. You don't want everything that's going on now with the concussions and stuff. You don't want guys to get knocked out. You want to see the stars of your football team to be able to show up and play.
"But you also don't want to take out what we love about this sport - how tough and how physical it is."