Would this also be for the drop in the 4500 RPM?
No!
The big dip at 4500 RPM is "calm before the storm". At 4500 RPM the ports are too big, the ports are open too long, the diffuser is too close to the piston causing severe short circuiting and over scavenging, the tail cone is sending the return pulse while the transfers are wide open, the velocity in the carburetor is too low..............every system in the engine is having a battle with other systems, nothing is working together and power suffers.
The torque peak occurs where the majority of the systems within the engine are optimally working together. Developing an engine where the torque peak and power peak occur at the same RPM is easier than producing an engine that has a wide flat torque curve or one that has the torque and power peaks separated by a wide RPM span.
Producing a wide torque curve requires the engine developer to make all of the systems that comprise the engine, to come into tune at slightly different RPMs.