You seem to be implying that commercial aircraft go missing over the ocean routinely. That's not the case.

The missing of MH370 itself is an outlier(, unprecedented according to the Malaysian officials), too. BTW, I was not implying anything.

It is extremely unlikely. They only have enough power for about 30 days, and they are generally only on reasonably large, commercial, aircraft, or on military aircraft.

If they picked up a black box, and it is not from MH370, then it would mean that another large commercial plane went down there within the last 30 days and either no one noticed it was missing or it was somehow kept secret, or that some military lost a plane there within the last 30 days and kept it secret.