Rick's whole character arc is basically will he become Negan or not. As of yet, IMO, he has not, but he has shown signs, and has done the things Cheese mentions. But he is still conflicted and his misdeeds have tended to be the result a rage rather than calculation. Rage is no excuse, but if I'm trying to compare the two as apples-to-apples: Negan routinely bashes heads in at random 'as a message,' steals people's wives, burns people's faces, throws people into fires, and forces people to fight zombies as minimum-wage labor. And is utterly convinced that he is saving people as he does. I assume we're being led to the question of whether Rick, in besting Negan, becomes him – or if Carl's vision stops him.
BTW - did we ever find out if someone from the Kingdom had their head bashed in? I think Ezekiel struck the deal at a distance to keep it from his people, but I can't remember what the first encounter was supposed to have been.