Cam being released came as a shock but it makes sense. Can is too high a profile of a player to be a backup for a rookie in the Patriots system. If Mac Jones struggles, the media will question when it is time for Cam to come in and replace him.
Whether the Patriots are winning or not, the cameras will pan over to Cam at least 5 times a game trying to catch his reaction. Hoping they catch him moping.
I see the best fit for Cam at this time is going to a struggling team that needs a solid insurance policy like Houston, Dallas, NYJ, or possibly the Rams to be ready in the event of injury or suspension. Can still has at least 2 more good years of service in him that a team can use to develop their future quarterback.