The New Zealand Cricket Players Association chief executive said New Zealand Cricket had sound concussion protocols in place and allowed substitutes in domestic one-day and twenty20 fixtures when there was a suspected concussion.
Australia has gone a step further and introduced dispensation to trial concussion substitutes in first-class cricket this season.
Mills would like to see NZC follow suit and believes more can be done to protect players.
''We've been talking with NZC for a couple of years about this and we've got good protocols in place now - in terms of the game being stopped and players being able to leave the field,'' Mills said.
''But I think the broader issue of concussion in sport in general is one we still need to keep asking questions about.''
''Concussion can be hard to diagnose and can have different impacts on different people. All sports need to do a lot more work on concussion to further understand the impact of it and how we can assess it and deal with it when instances occur on the field.''
Internationally, cricket has resisted introducing laws which would allow substitutions but Mills believes it is ''something we need to look at''.
''We need to have a discussion about international cricket and whether we can have substitutes or not, because there is all sorts of pressures on players to continue - not just from the players themselves but also potentially from the management, depending on the game situation.
''Cricket has been unusual in that it hasn't had substitutes but I think that is something the game is going to have to [think about] more and more.''
The protocols in place in the Super Smash and one-day competition allow the umpire to stop the game if a player has been hit in the head.
The team's physiotherapists, who have received training in assessing concussion, put the players through the same test New Zealand's professional rugby players undergo.
The results are compared with a baseline from the start of the season. If there is any doubt, the physiotherapists are expected to err on the side of caution and have the player replaced.
Internationally, though, the approach is varied.
''There is no question everybody seems to be operating in isolation at the moment trying to find the best way to manage what is a really difficult and challenging issue,'' Mills said.
''From our point of view, we want to make sure that the players are safe and that there is good protocols in place.
''We feel like we've made good progress with New Zealand Cricket. But there is no question that more needs to be done internationally in sport with how we deal with concussion.''
