These feel like two very important moments. Crowley calls Sam the Scarecrow and Dean the Tin Man.
The Scarecrow was missing his brain, but really he was the smartest one of the bunch, coming up with all of the best plans. This is Sammy, the bookworm and true Man of Letters. It can also be a reference to the fact that Sam’s mind is currently being manipulated by Ezekiel.
The Tin Man was missing his heart but loved everyone so deeply that his own emotional tears caused him to freeze up from rust. The Tin Man doesn’t think he has a heart but in the end, he finds out he had one all along. This parallels Dean, who just last week told Ezekiel that he doesn’t ‘do the whole love and…love.’ But in truth, Dean loves the people he is close to fiercely, willing to do just about anything for them (including lie, kill, die and make shady deals). Dean’s capacity for love is what has broken possession and mind control repeatedly and is what keeps Sam, Kevin, Cas and Charlie (not to mention Jo, Bobby, etc…) drawn to him.
Later in the episode, Dorothy holds up the head of the Tin Man and says that he didn’t make it. Yikes! If the Tin Man is parallel to Dean, could this be foreshadowing? If we are heading down the path of End!Verse, could this lead to Dean’s death?