Built for the trade deadline
Mid-season trades are about the weeks that are left, not the weeks that are gone. The analyzer only counts projected points from now through week 17, so a player who is about to come off a bye is worth more than one whose bye is still ahead, and a player on injured reserve is worth very little in a redraft league no matter what he did in September.
What the adjustments mean
When the sides have a different number of players, two adjustments appear next to the totals. The side receiving fewer players earns a consolidation bonus if it gets the best player in the deal. The side receiving more players pays a roster spot cost, roughly what a waiver pickup is worth, for every extra player it has to roster. The full logic is on the methodology page.
Not sure about a lineup decision instead? Try start/sit. Looking for someone to trade for? The trade value chart lists every player's value by position.