"The reality is neither of those scores [in India] are good enough, even if India won both tosses. You can't give the opposition a lead of 100-plus.
"A lot of our chats have been about the first 15 balls. Some other countries you can come out to bat and the ball's not doing much. You can face a straight one.
"Here the ball is moving constantly through the 80 overs so your footwork and mental adjustment at the start of an innings is crucial, and we've lost three to four quick wickets [on occasion] because of those challenges."
One theory is that players' confidence is threatened without the comfort they can go to the Decision Review System, now a commonplace scenario outside Indian tests to insure against howlers.
"We've got to play straight and trust our defence and have a positive mindset," stand-in captain Ross Taylor said in reference to the lack of DRS in the second test loss.
"It's easy to get insular over here. You've got to trust your game plan."
On the plus side yesterday, McMillan delivered about half an hour of throwdowns to Kane Williamson who looks set to recover from his viral illness in time for the match.
"He hasn't picked up a bat for close to a week. He had a nice, easy day hitting balls and getting his body back into the rigours of batting again," McMillan said.
"The focus was not on footwork or technique. It was just about swinging the bat, getting some power back in his arms and feeling the timing return.
"You can see the colour coming back into his face. It was certainly encouraging."
McMillan also revealed his advice for Martin Guptill, who is struggling at opener.
"Keep leaving [the ball]. He's not far off. He hasn't scored the weight of runs he's after and he's made some mistakes but that happens from time to time.
"He's also been unlucky, like getting one that bounced off his elbow into the stumps. My message to him is don't get too down on yourself. He's due."