I'm not too sure you are comparing like with like.
I'm no expert on the old system (or the new one really) but with the newer system an Alternate Control Braking Unit (ABCU) using the Ylo system comes into action, if Grn Hyds Px is insufficient, and provides Alt braking with Anti skid.
If the anti skid is inop (switched off or various Y and or G hyd faults) then you get alt brakes without anti skid using Ylo px (if available) or the accumulators which are automatically limited to 1000psi application pressure.
If you've got access, FCOM 1.32.30 summarises it quite well (for a change!).