He’s out of a cast, but when will Dolphins quarterback Ryan Tannehill be back on the field? Per a source with knowledge of the situation, the week-to-week scenario has now become day-to-day for Tannehill, who suffered 15 days ago a Grade II MCL sprain and a slight tear of his ACL on a low hit from Cardinals defensive lineman Calais Campbell. With the cast, which was used to stabilize the knee so that the MCL could heal, now gone the question becomes whether the MCL has healed enough to let Tannehill play. There’s also a question regarding whether the Dolphins are comfortable letting Tannehill play at all with a slightly torn ACL. As NBC Sports Medicine Analyst Mike Ryan explained in the aftermath of the injury on PFT Live, the ACL doesn’t heal itself. So the damage will never get better on its own — and it could always get worse.