  We critically assess the role of the Blandford-Znajek mechanism in the
powering of outflows from accretion disk-fed black holes. We argue that there
is no reason to suppose that the magnetic field threading the central spinning
black hole differs significantly in strength from that threading the central
regions of the disk. In this case, we show that the electromagnetic output from
the inner disk regions is expected in general to dominate over that from the
hole. Thus the spin (or not) of the hole is probably irrelevant to the expected
electromagnetic power output from the system. We also point out that the
strength of the poloidal field in the center of a standard accretion disk has
been generally overestimated, and discuss scenarios which might give rise to
more significant central poloidal fields.
