There is a work around in an online franchise to make sure certain guys hit free agency. Use the superbowl as your starting point. For your character pick one of the players that you want to be a free agent. In week 1 of the offseason ask to be released, then retire that character and create a new one as the next player that you want to be a free agent. Unfortunately in an online franchise you can only have one character at a time so you wont be able to control multiple teams to make sure the free agents are signed by their correct teams.
There is another possible work around, I haven't tried it because it would be a big time commitment. If you started an offline franchise you could use the force win feature for every week to get the correct record and standings. In an offline franchise you can create multiple characters so you could take control of the teams you need to, I believe there is a way to set up 32 team control. The big downside to this is you wont get the correct stats for the season.
I don't get why we can't use the feature where you can start at any point during the actual season in an offline franchise. It would make much easier for guys like us that like to try replicate the actual offseason or as close to it as we can.