did not give good effort due to that and when his number was not called to run. He is a back that does an adequate job when the play call is a run between two offensive positions and the whole is there for him.
How many times did he get the ball and proceed to take an expeditious route into the backs of a couple of blockers for no gain or a loss?
How many blocking assignments did he miss allowing pressure or a sack?

McMillan's one positive attribute was speed if he found himself in the open field. He has poor vision, does not make people miss in the open field, lacks effort when his number isn't called to run the ball, and sulked when he was taken off of the field for various reasons.

The right back for this system is one who exhibits these qualities plus has good hands in the passing game and not a unrealistic expectation to run the ball thirty times a game. Unfortunately all of these worked against McMillan to his detriment and he was not able to overcome these issues with speed alone.