I have been out of the hbd game for a few years. I was wondering what the colored dots mean? Also, can anybody give me a guideline of how well a players defensive ratings should be based on position. Thank you

1. You can set the dots yourself to whatever you want them to mean. Popular uses are to track quality prospects, to tag potential players to trade for, put them on your Enemy's List, etc.
2. On the GM screen, click the position that the player is listed for (to the right of the player name). That will pop up a window of suggested/average defensive values for each position.