Bronze isn't "in the way" in BAEC. You don't reset the year when you level up.
Bear in mind the benefits of BAEC Silver are across oneworld airlines as oneworld Sapphire, whereas MPC Silver is only oneworld Ruby which doesn't really offer much. But if you mean that with MPC you'll direct your flights to CX only (and not, say, JL or MH or even BA or QR), that may not matter.