I got upgraded by IB from plata to oro (silver to gold) 2 weeks ago. I was pretty close to gold anyways.
I'm guessing that they did something similar to BA, where the requirements for the levels were relaxed ~30%.
From the email in spanish:
Por esta razón hemos querido flexibilizar las condiciones del programa. Dado que ha bajado notablemente la actividad aérea en estos 3 últimos meses, hemos reducido las exigencias del programa de forma proporcional para que así te conviertas en socio Iberia Plus Oro.