The Kangaroos came from behind to defeat the Western Bulldogs at Eureka Stadium last Saturday, but were set back by a hamstring injury to forward Matt Campbell.
Coach Brad Scott was scathing of the rule after the match, a sentiment echoed by McDonald on Tuesday.
"We were pretty exposed on the weekend in terms of some of the injuries we had. In terms of a review, we have a fantastic medical and conditioning team. From a positive side, we kicked 18 goals against a potential top four side and we kicked nine in the last quarter," McDonald said.
"I think it's going to be an issue. Whenever you introduce something new, it's going to be subject to close scrutiny by the clubs and the media.
While the Kangaroos came away with the win, the Bulldogs rested several key players in the final term, which may have played a part in the comeback.
McDonald said the impact of an early injury would be more telling when premiership points were up for grabs.
"If it was in the season-proper and that same scenario happens, in that someone got injured early, everyone is saying the sub may be used from a tactical point of view but if you lose someone in the first five minutes with a hamstring, all of a sudden you're down to three and there's no advantage," he said.
"The number one thing that we've always got to be mindful of is the players, their longevity and looking after them.''
The Kangaroos also had to cope with injuries to Sam Wright (concussion) and Brady Rawlings (hamstring), forcing Aaron Edwards to play out the game with a corked thigh.
"We can only talk from our own experiences and the weekend was the first time we decided on only three interchange players and by three-quarter time we didn't have a fit interchange guy on the bench.''
