I have a complex set of transaction variables, like in the real MLB. From a minors perspective, there are two levels, true rookies determine by stats, or optional assignment. Have a bad contract? There are 3 ways to let a player go. Waive, designate for assignment, or buyout. But you can only use each one once a season.
Minor league contracts, contract option extension are all part of how the contracts work. This will be a complex league, but a fun one. The hard work is on the commissioner, not on the owner.