With the new rookie salary pool (“rookie cap”), as instituted by the league’s 2011 CBA, there really isn’t a lot of mystery about the size and scope of rookie contracts as is it basically now a slotted system.
For early 1st round picks, offset language can often be an issue. Since high draft picks receive fully guaranteed contracts, teams often look for offset language which allows them to recoup some or all of the future guaranteed money if the player since elsewhere. Just how much of the guaranteed money is included in the offsets is the subject of negotiation.