Hmm...I'm not sure that contentious is what they meant with the poll. Here, I'll submit a PC from one of my games and people please tell me if he fits the definition of adversarial (I'll call him Dhistan because that's his favourite PC):
The evil: In real life, Dhistan would be Lawful Evil if we had alignments. He enjoys creating evil characters, and his good characters always wind up merely doing good deeds that result in his own self-interest in some way. Dhistan's characters like money and power more than anything else. If he thought he could get away with it and that it would give him more of an advantage, Dhistan's characters would kill the rest of the party and sell their souls to Hell, but since his allies are formidable, he prefers to keep them alive. Nevertheless, when he wants to buy something, he does not hesitate to steal all their gold. In fact, they were trusting their treasure to his character's sister, so he stole it all, framed his sister (an NPC), convinced the party that she was an evil demonologist who was stealing their gold, and banished her to the shadow plane for all eternity. When the Frenzied Berserker swore to protect a barbarian village, Dhistan came in and massacred them all, women and children included, and sent the souls directly to Bel. He definitely sees the world as him-against-everyone-else, and he plans out his character 20 levels in advance in hopes of achieving even greater levels of power. Dhistan is in this for power and the fact that he loves seeing how his evil schemes turn out and affect the world.
The lawful: That said, when his evil schemes fail, Dhistan does not get upset. He justs comes up with a new one. He has a strong respect both for the rules of the game and for my authority as a DM to make calls that aren't specifically stated in the rules, whether they are for or against his character. In fact, he agrees with me on rules calls so much that he will often bring up my calls when he is playing with other DMs who have to make similar decisions to be helpful. Although he respects the rules, he is not a rules-lawyer and does not attempt to make rules-contentions to slow down the game. He does not metagame to destroy plots, although sometimes his actions lead into non-sequitirs to the main quest that must be dealt with, which is fine with me, as I can wing it. He is always polite to the other players and gives everyone a turn, even when he is trying to murder their cohort and blame it on his mother. In fact, if he feels that he has been taking too much time in the game's spotlight, he asks the other players their opinion, and if they agree, he voluntarily retreats out of the spotlight into the shadows, planning his next evil scheme.
So, is he an adversarial player? By Wolf's definition I would say "Yes." By your definition Metal I would say "No." That's what makes me think that they didn't mean contentious