Kenny Rausch spent one evening during the coronavirus-induced void of live sports watching a re-run of the Stanley Cup Finals from the early 1980s.
So, just a few months later, when he tuned into the 2020 playoffs from the Edmonton Bubble, the differences in the game couldn't have been more pronounced.
One play in particular stood out to the director of youth hockey for USA Hockey when Dallas Stars defenseman Jamie Oleksiak took an outlet pass from defense partner Miro Heiskanen, who then joined him in a 2-on-1 that resulted in a breakaway goal against the Vegas Golden Knights.
"If that would have happened back in the 1980s, your coaches in youth hockey would have been screaming at you, and your mom and dad would be screaming at you to get back because you're a defenseman," Rausch said with a laugh.
"Can you imagine? Two defensemen leading a 2-on-1 rush? I know Paul Coffey started to change the game a little back then because he was such a great skater, but certainly Charlie Huddy wasn't joining the rush with him.
"I still have disagreements with my father, who's 75 years old and coached me growing up, about the way the game is played today. He'll say, 'It's not what we did.' I know Dad, but this is 2020 right now. It's not 1975."
Rausch believes, "This is the way we've always done it," could be one of the most dangerous phrases in the human language.
So much has changed about the game, and not just the size and the speed of the players but also the way it's played. Toughness and intimidation have been replaced by speed and skill that is supported by long-overdue safety and respect initiatives.
Because the game is played more with concepts and habits, more coaches focus on teaching creativity. Analytics have proven the old dump-and-chase style doesn't make as much sense as puck possession. And, yes, defensemen can jump into the offense.
"The game is constantly evolving, and you always want to know what the next system is going to be," said Terry Ruskowski, who played 15 years in the rough-and-tumble days of the WHA and NHL from 1974 to 1989, coached minor league hockey for more than 20 years.
"When Philadelphia won the championship in the mid-1970s, everyone went for toughness. When Edmonton won, everyone went for skill and speed. And then when New Jersey won, everyone did the trap," said Ruskowski, who now works with the youth hockey program in McKinney, Texas.
"If you don't keep up with the times, you're going to be behind the times and you're not going to win hockey games."
USA Hockey aimed to help coaches shed their old ways of thinking when it introduced the American Development Model in 2009. The ADM offered a blueprint for considerably more efficient and age-appropriate skill development. And it created opportunities for high-performance hockey at every level on the player's development journey.
"When the ADM first got rolled out, there were a lot of questions on why it was being implemented, and a lot of coaches weren't completely on board," said Doug Dietz, a Waterloo, Iowa, native and the Central District Coach in Chief for USA Hockey. "But as time has progressed, coaches have started to see the success and understand why the change was being made."
In Dietz's opinion, the most successful coaches are the ones that have an open mind and evolve their coaching styles as the game progresses.
"Good coaches take drills and systems from other coaches and implement them into their own game plan, which is what USA Hockey has done. They looked at Sweden and looked at Finland and brought a lot of their materials into their own mixing pot in developing the ADM," Dietz said.
"The results speak for themselves. We're seeing more and more kids from non-traditional areas get the opportunity to advance their hockey careers, and we're seeing more kids stay active in the sport longer."
But the ADM also gives the coach a little freedom to think outside the box. 
"The blueprint is the blueprint, but different people break things down differently in a way that the kids understand better, so you can get creative," said two-time Olympian Guy Gosselin who is a member of USA Hockey's ADM staff.
"We always talk about clear and concise instruction and getting them out there moving. Kids are out there to play, and they learn by playing. You just have to find the right way to provide that atmosphere out on the ice."
Because the game has changed, coaches have no other choice but to adapt. If they don't, their players will be left behind.
"We ask coaches to have that open mind and to put the players first and put them in the environment of what today's game asks of them," Rausch said. "You really have to be like a Swiss Army Knife. You may line up in a certain position, like [the Buffalo Sabres'] Rasmus Dahlin may line up at left defense, but does he really play left defense? Let them play situational hockey, not necessarily defined by a position."
The mindset of the player has changed dramatically over the years, too. Today's youth learns differently and has significantly more access to information. Children can pick up an iPad or their cell phone, watch a 20-second instructional video and immediately want to try something new on the ice.
"Without question, the 21st century child is a lot different than when I was a kid," said long-time Providence College women's coach Bob Deraney, who now mentors coaches in the Boch Blazers youth program in Chatham, Mass.
"When I was a kid, the coach told you what to do and you did it. No questions asked. In the 21stcentury, it has to be a collaboration."
Deraney appreciates the inquisitive mind of today's youth.
"You want to make the players feel like they can ask why and not just say, 'Because I said so,'" he said. "There is no credibility in that anymore. Kids are smarter now because they have access to more information."
The coaching styles may have changed over the years, but instilling a passion for the game and teaching the skills to succeed are no less rewarding.
"This is the first time in my life as a coach that the kids have come up to me and given me a fist pump and thanked me for a practice," Ruskowski said.
"I was flabbergasted the first time that happened. It's so nice to see the appreciation from the boys. It makes me feel a little bit better, knowing I'm doing something they appreciate, and it'll lead to success for them not only this year but down the road when they continue playing hockey."
Jim Leitner is a freelance writer based in Dubuque, Iowa.