Boughner is no pacifist. He had 105 fights during his 10-season N.H.L. playing career, and with him behind the bench last season, the Spitfires’ 101 fights led the O.H.L. by a wide margin. They lead again this season but are on pace to finish with 90.

The O.H.L., a major junior league for players between 15 and 20 years old, sends more players to the N.H.L. than any other development league. The league’s president, David Branch, is seen as the leader in reforming the game at the major junior level. He imposed penalties for hits to the head four years before the N.H.L. did, and in 2009, he made a player subject to suspension for removing his helmet to fight.

The 10-fight rule is the latest in a series of small steps to reduce fighting and, as he put it last season, “evolve away from it.”

But hockey traditionalists offer plenty of resistance. Some critics say that curbs on fighting will make the game more dangerous. With the 10-fight limit constraining enforcers, they argue, nothing will stop players from taking cheap shots at opponents.

“What fighting does in hockey is give accountability,” Ken Belanger, a former N.H.L. enforcer, said recently on “Hockey This Morning” on SiriusXM satellite radio. “Players have to play with repercussions,” he said. “They have to know that if they cross the line, they have to pay a price. How am I supposed to thank my buddy if I’m laying on the ice hurt after a guy crosschecked me, and he can’t do nothing but say, ‘Hey, are you O.K.?’ And the other guy’s skating around laughing?”

Others like Brian McGrattan, a frequent fighter with the Nashville Predators, say the limit will make O.H.L. alumni more vulnerable to injury when they graduate to the N.H.L.

In September, McGrattan wrote on Twitter, “Feel sorry for those kids that cant fight in junior and are gonna have to learn the hard way in pro gettin their head punched in.”