Zorzii, this is not so uncommon. I assume the player complained about playing time at least once over the season. That was your warning that this was going to happen. It's a weird part of the game, but I think Sophomores expect to play around 10-12 minutes. So when they complain, get them more minutes.
I assume you are referring to your Knight team, which I checked and plays man 2 man. This the downside of playing m2m or zone, because in those sets you can easily play a 10 man rotation, so you get 2 guys playing around 5 mpg or less, which means when you have a large class, someone will be upset about minutes. Just something to be aware of in the future.