Red bars for player time?

[cdubb]

I'm getting back into 2k16 after not having played for a while. I just noticed the playing time bar going from green to red while playing myGM in some instances. I assume this red bar means it's a risk to play the player that length of time? Possibly induce injury or tire easily? If this is the case, I thought it was odd that when I ask the assistant coach to set my lineup, he still plays players into the red.