If a precipitous rise in oil prices caused inflation, why did Paul Volcker cure it, and not the equally-precipitous fall in oil prices that occurred simultaneou

If a precipitous rise in oil prices caused inflation, why did Paul Volcker cure it, and not the equally-precipitous fall in oil prices that occurred simultaneously with his attempt? That is, second attempt -- his first attempt, when oil prices were still high, didn't work.