You gotta be kiding, there are countless number of managers in any big4, it is a standard title anyone who doesnt screw up will get after 2 years Associate + 2-3 years Senior Associate.

Unlesss you are including all those non-professional staff like clerks, adminsitrators, receptionist, shared services etc, a manager in big4 both in rank and pay is pretty low in the entire heirachy.

Associate Directors/Directors are more considered middle level. Do not be misled by fancy titles in the finance/consulting industry.