I disagree that an alpha dog has to be taking the last shot, or creating the last shot. You can have a star player that is the clear cut leader of the team (KG for example) who I would say is the alpha dog of his team, yet didn't always have the ball in his hands at the end of games. Sure, you could put the ball in his hands because he's "the alpha dog", but I would rather have the ball in Rondo's hands because he is one of the best in the league at creating high percentage shots
To elaborate your point, Boston's alpha dog is KG. Yet the ball isn't in his hands, but in Rondo's. BUT, also, Rondo is using his ability to find the shot for Allen (Heat), for Pierce, and now for Terry.