It depends on what Mike McCarthy's demands were. As a former Super Bowl winning head coach, with a strong track record, he might have wanted final say over the roster and perhaps even greater control and influence than the Jets were willing to give him. Whereas Gase is more likely to have accepted less control in personnel in order to get another opportunity.
The only other reason I can think of is that perhaps they felt Case's downfall with us was the quarterback situation. He worked as a QB coach with Tebow when the Broncos made the play offs with him, did a fair job with the Bears and Cutler, and with us Tannehill did improve. McCarthy on the other hand has only dealt with Rodgers, would McCarthy have had success without him? Hard to say. Would Rodgers still have been great without McCarthy? I'd say there's a good chance he would.
So perhaps the Jets felt that Gase could do more with Darnold than McCarthy could because of who Gase has had to work with and the improvement he's got out of those quarterbacks (Tebow, Cutler, Tannehill)? Granted it's a stretch, but maybe they think Gase can finally run his offense with a top prospect under centre in Darnold, and help Darnold reach that next level. Obviously I have my doubts about this, but who knows, maybe Gase will surprise everyone?!
