McMillan craves certainty and stability, and isolation offense with a great creative scorer is among the most stable forms of offense in the NBA.
If you could hack into McMillan's basketball-related dreams, I think what you'd find is a team that plays great defense, takes care of the ball and plays isolation basketball with a durable star. It's about as stable a winning formula as you could create. McMillan would probably call it "playing the odds" to make it as hard for an opposing team to beat you.
And he wouldn't be completely wrong, if that is what he said. Isolation ball is pretty successful when you have a star. Complex motion offense have a higher ceiling but also a much lower floor. Unsuccessful motion offenses are turnover and bad shot machines. Running a successful motion offense, at the NBA level, takes a number of smart, versatile and high-caliber athletes and a creative offensive mind. Very few NBA head coaches are creative offensive minds. Tom Thibodeau is a well-respected coach and he's not a creative offensive mind (though he's a smart defensive coach). Last year, he coached the exact team McMillan wants...a tough, disciplined defense and an isolation offense for his durable star Derrick Rose.
It wasn't a great offense, but it was successful enough (and they played at a low pace). Combined with their defense, they were a top team.
McMillan has failed to create that kind of defense, which is more the problem than the offense he's run. I do think he's weak in terms of making changes to the lineup (but he's strong in getting the team to overcome adversity, a skill he's unfortunately had many chances to utilize). I'm not a major McMillan supporter, but I don't have much problem with what he did offensively when Roy was at the top of his game.