Back in the 1970s, hockey was characterized by violence more than anything else. Whether it was the “Broad Street Bullies” (Philadelphia Flyers) or the “Big Bad Bruins” (Boston Bruins), physical strength and intimidation played as important a role in on-ice success as did the crisp playmaking of teams like the Montreal Canadiens.

In recent years, the NHL has taken a complete 180° turn away from the style of play that reigned supreme in the early to mid 1970s. The instigator rule has eliminated much of the vigilante justice that once served as a deterrent against chippy play; the league instead relies upon aggressive penalty-calling and harsh suspensions to eliminate violent stick-work.

But the unintended consequence is that the sport has lost much of its physicality. Where the area in front of the goal crease used to be noman’s land for opposing forwards, it is today a safe haven for even the league’s most diminutive players. And a generation of fans weaned on a violence-laden NHL is feeling as though the league they once loved is now dead and gone.

Finding a solution to this problem has proven to be incredibly difficult for the NHL. The postlockout schedule, with a heavy emphasis on divisional play, was intended to foster rivalries. “Familiarity breeds contempt,” or so it was supposed to go. But a look back at the NHL’s most compelling rivalries yields a conclusion that the powers-that-be probably won’t like. Virtually every major rivalry was borne not by geographic proximity, but by violence. In fact, the best rivalry the NHL has seen in recent memory involved two teams that were 1,300 miles apart.

In the 1990s, it could fairly be argued that the rivalry between the Detroit Red Wings and Colorado Avalanche was not only the NHL’s best, but the most compelling rivalry in all of professional sports. While it’s certainly true that the two teams were consistently amongst the Western Conference’s best, the only reason that rivalry reached a boiling point was because Colorado forward Claude Lemieux delivered a brutal hit from behind to the Wings’ Kris Draper. Draper’s face required serious reconstructive surgery, and a series of “grudge matches” that followed provided the fuel needed to light the bonfire.

In the spring of 2004, an ugly incident involving the Avalanche and Vancouver Canucks cast a looming shadow over the NHL. In retaliation for an illegal but unintentional hit to Vancouver captain Markus Naslund’s head by the Avs’ Steve Moore (that correctly yielded no suspension), the Canucks decided to take matters into their own hands. Vancouver forward Brad May announced that there was a “bounty” on Moore’s head after the incident. And in the first rematch between the teams in Vancouver, Canucks forward Todd Bertuzzi delivered a sucker punch to Moore’s head that effectively ended his playing career.

But where the incident might once have fueled a high-octane rivalry, it instead fizzled out. Bertuzzi was issued a long suspension, and he was permitted to return to the ice when the lockout ended. Where May might once have been “Public Enemy Number Two” in Denver, the Avs instead actually signed him to a free agent contract in the summer of 2005. And so, instead of taking the good (a new, great rivalry) with the bad (an ugly, violent incident), the NHL suffered the incident without gaining a single thing from it.

When the response to an injury is a substantial suspension, the league is essentially pouring water on the flames. When the response is to ignore it, the flames are instead doused with gasoline, likely igniting a full-blown rivalry that fills seats and generates tremendous excitement throughout the hockey world. It also begets more violence, of course, but in an America where ultimate fighting is experiencing an exponential rise in popularity — while the NHL is losing its market share — there is little question as to whether the league would profit by “letting the boys be boys” a bit more often.

In a 1979 playoff game, the Islanders’ Denis Potvin broke Rangers forward Ulf Nilsson’s leg with a legal bodycheck, and it spawned a chant — Potvin S***s! — that to this day is heard at every Rangers game played at Madison Square Garden. The incident poured gasoline on the flames of the cross-town rivalry, and is a key reason why virtually every Islanders-Rangers game is to this day a guaranteed sellout.

Today, hockey resembles soccer more than any sport. While it’s true that soccer’s popularity throughout the world is unparalleled, it is still struggling to gain traction in America. The L.A. Galaxy and MLS spent $250 million last week and signed the sport’s most recognizable personality — English superstar David Beckham — in an attempt to address the problem.

Every sign indicates that the NHL’s powers-that-be must take dramatic action, which is why the league has made so many changes in such a short time. But while minor tweaks like eliminating the two-line pass rule and cracking down on obstruction have certainly improved the flow of the games, there’s a serious problem when every game has a similar energy level. Rivalries generate excitement. And though the league tried to acknowledge this by modifying the schedule to increase the number of games between geographically proximate teams, it has ignored the reality that hockey’s best rivalries have been fueled by violence.

Put simply, violence and NHL hockey have been inextricably linked for decades. In its attempt to change that, the NHL is taking a very dangerous risk. If it continues to alienate its existing fan base, there is little reason to believe that a new fan base will emerge to counterbalance the losses. The NHL was once without question one of America’s four major sports, but today it is struggling to rediscover its identity. That is indeed a very treacherous road to traverse.

Mr. Greenstein is the editor in chief of InsideHockey.com.