You ablated a head and the model got worse at everything

You are investigating which attention head implements a name-copying behaviour in GPT-2 medium. You zero-ablate head 9.6 and the behaviour degrades substantially: the logit difference between the correct and incorrect name falls by 2.1.

You also notice that on a set of unrelated control prompts, average loss rises by 0.4. And when you ablate a randomly chosen head instead, the target logit difference falls by 0.3 and control loss rises by 0.15.

You are about to write that head 9.6 implements name copying.

What can you legitimately conclude from this evidence, what can you not, and what experiments would you need before that claim is defensible? Be specific about what each additional experiment rules out.