The death of Phillip Hughes, a batsman for Australia’s cricket team, during a domestic match in 2014 changed the sport in his country and beyond. It accelerated changes to helmet technology and regulations on wearing them in professional cricket. It prompted a detailed inquest into whether his death could have been avoided and raised questions about how the sport could be made safer.
It also led to more significant changes. Last year, Australia introduced concussion substitutes to domestic one-day and Twenty20 matches, a momentous step in a sport that, except for a brief experiment in 2005 in one-day international matches, has never allowed substitutes.
Yet there is growing anger that changes to protect players’ safety do not go far enough. Under International Cricket Council rules, all first-class club matches as well as all international matches still prohibit substitutes, even for head injuries.
“We would like to see concussion substitutes introduced both into first-class and international cricket,” said Tony Irish, the executive chairman of the Federation of International Cricketers’ Associations, the sport’s global players’ association. “We see this as an important health and safety issue for players and believe that cricket is behind other sports in dealing with it.”
Cricket Australia has lobbied the I.C.C., the sport’s worldwide governing body, to allow concussion substitutes in first-class cricket, but its formal request to permit
 the rules change was rejected in June. As a result, concussion substitutes are permitted only in domestic 50-over or Twenty20 matches, and only if the relevant national governing body decides to introduce them. So far, only Australia and New Zealand have made the change.
Aaron Finch, an Australian batsman, had to stand in as wicketkeeper three times in recent months when teammates with head injuries were forced out of matches while playing the position. Wicketkeeper is a particularly vulnerable position in cricket, the equivalent of a catcher in baseball.
“It’s a dangerous position,” Finch said recently, “and if someone is in there and is not qualified or doesn’t have the right tools to do the job, then it becomes even more dangerous.”
A string of episodes in recent months have brought back memories of Hughes’s death and instilled new urgency into the question of whether cricket’s governing bodies could do more to protect players. In January, Matt Renshaw of Australia was struck on the head twice in three days — first while batting, then while fielding — and was withdrawn from the remainder of a Test match with a concussion.
Last month, Sam Harper, a player for Victoria, was hospitalized after he was hit on the head during a first-class match in Australia. Victoria asked to be allowed a replacement player, but its opponent, South Australia, rejected the request. If the request had been granted, Victoria could have been docked points, and the match would have lost its status as a first-class game.
There also remains no standard protocol across all professional matches, even in international cricket, on how to deal with head injuries. When Pakistan toured Australia recently, it did not have a traveling team doctor, and after a player was hit on the head during a Test match, it was left to the player to decide whether to return to the game.
“There is need” for universal guidelines on head injuries, said Irish, and for them “not to simply be viewed as another injury.”
Australia is leading a renewed attempt, with England, South Africa and New Zealand, to urge the I.C.C. to permit concussion substitutes in first-class cricket, yet the tradition-bound I.C.C. has shown little appetite for the change.
“I’m hesitant to tinker with the laws of cricket,” David Richardson, the I.C.C. chief executive, said recently. “Concussion occurs so infrequently it’s probably not an issue.”
The I.C.C. is distributing guidance to all member countries to improve the medical management of head injuries, but there are “no immediate plans” to revisit the concept of concussion substitutes, a spokesman said.
Supporters argue that concussion substitutes would not only help safeguard players, but also make the game fairer.
“You don’t want people to be playing with 10 men because someone got hit with a cricket bat,” Matthew Wade, an Australia wicketkeeper, said.
Concussions can shape a match by ruling a player out for the remainder of the game. In 2006, Justin Langer of Australia was struck on the head by the first ball he saw in a five-day Test match and left with a concussion. He did not bat again in the match.
Tradition — Test matches have been exclusively 11-a-side affairs since their inception in 1877 — contributes to cricket’s reluctance to embrace substitutes. So does a feeling that allowing concussion substitutes might invite abuse by teams merely looking to make a lineup change or to alter the momentum of a match. Langer, now a leading coach, recently said he was worried that teams could exploit “loopholes” in the law.
One solution, advocated by Cricket Australia, is to explore introducing substitutes for all injuries.
“There is room for broader consideration of a substitute in Test cricket,” said James Sutherland, the chief executive of Cricket Australia. “Most other team sports allow a substitute, and I think that in a five-day match, the penalty for losing a player from injury during a game is quite severe.”