What is the best structure for the existing code?

Again and again. Don't put CSV parsing code in the DTO, much less in the constructor. Don't abuse the advice tag to ask for a code review. Post at https://codereview.stackexchange.com/ and listen to what people say.

There are several problems with this code, some already mentioned. I won't post them here though. Post at https://codereview.stackexchange.com/

If you have working code, it is better to post it in Code Review Stack Exchange.

For future reference when recommending the Code Review site, please provide the link to the Code Review Help section rather than the questions. In the current form of this question it is off-topic on Code Review.

Anything that can be converted to an enum such as Position should be. Ex public enum Position {PointGuard, ShootingGuard, SmallForward, PowerForward,Center}. var forwards Players.where(x => x.Position == Position.SmallFoward || x.Position == Position.PowerForward);