The Post's editorial on the numbers of political appointees in the Senior Executive Service and lower ranks {"Government Workers at Home," Aug. 10} trivializes the importance of this development. While the Reagan administration may be operating within the legally prescribed limits for political appointees, it nevertheless has contributed to what is now a 35-year trend that threatens to erode the quality of government service.

The Post is right in concluding that "the civil service will survive," but the more important question is: "Will it be any good?" As a recently retired member of the Senior Foreign Service, where a similar trend is evident among both senior positions in the Department of State and chiefs of mission abroad, I know that the question is a valid one there too.

Raw numbers and percentages of the sort contained in the GAO study for Sen. John Glenn risk obscuring the real question of how these trends affect the capacity of government agencies to carry out their responsibilities. It is no accident that several of the departments mentioned in that study with high percentages of political appointees have experienced declining morale, high turnover rates in both political and career cadres and a sustained overall record of inadequate performance.

All this is not to suggest a lack of competence among these political appointees. By no means; most are highly skilled, however limited their experience in their assigned area of focus. Nor is it to imply that an administration should not be concerned about personnel assignments that help ensure implementation of its political agenda. The point is that increased politicization of senior ranks is a management style that risks shutting out expertise and experience that can be crucial to achievement of the immediate policy objectives of an administration and to effective government service over the longer term.

In the worst cases, recent years have seen examples of top officials practicing forms of "jigsaw puzzle management," where senior career officials are deliberately kept in the dark as to the real policy objectives of the agency. When that happens, the prospect for program fiascoes increases. A far preferable practice is for career officials to be brought into top management teams in ways that blend their institutional memory and substantive expertise with the policy objectives of political appointees. The Environment Protection Agency is an example of an agency that has experienced both styles during the Reagan era.

The important point is that from numbers alone we can't tell which style will be used. But one thing is certain: an excessive number of political slots tempts political appointees to resort to management practices that isolate the top of the career services into decidedly secondary roles.

Any administration must rely fundamentally on the career services of government if its political agendas are to succeed. The quality of those career services will depend on many factors, but surely a central one is the administration's attitude toward its members, evidenced especially in assignments of and reliance on the senior ranks. In a word, trust. Increased politicization, both apparent and real, speaks of a lack of trust and over time will seriously detract from the spirit, the commitment and the work product of government's senior servants. The fact of serious attrition rates from the ranks of the SES since its creation in 1979 speaks volumes on the problem.

Yes, there was good reason for Glenn to be upset. The numbers cited in the GAO study are important, and several recent presidents are accountable for their increase and the costs they risk incurring. -- L. Bruce Laingen