Thank you for your interest in TeamPulse.
In the moment there is no automatically change for the assigned to field. However if you change the assigned to field in the TFS it will be automatically updated in TeamPulse. You can read more about how assign to fields is synced here.
If you want to change the assigned to field of an item when you change it's status, then you can go and create feedback item in out Feedback Portal, so we can review it and include it in our roadmap.
If you have any other ideas do not hesitate to contact us again.