MARION BARRY has often shown a talent for selecting quality professionals at the highest levels of city government--people who have brought technical expertise and a fresh management style. While there are still offices and agencies that do not respond efficiently to the citizens' needs, the administrative oversight at the District Building has been strengthened considerably since the earliest days of self-government.

Now the mayor has redesigned the top jobs in his administration, switching to a team of deputy mayors who will oversee the consolidation of various agencies and functions. And though he has suffered a loss with the departure of Elijah Rogers as city administrator, the mayor has made two new appointments ensuring continued high-level expertise. Thomas M. Downs, named as city administrator/deputy mayor and John E. Touchstone, chosen to replace Mr. Downs as public works director, have won high marks from colleagues in local government and federal administrators as well.

In both of these appointments, Mr. Barry has had an eye less to the political ramifications than to efficiency in government. In each case, the appointee faces complicated if not unusual challenges: budget constraints, interagency disagreements, entrenched lower-level staffers with less-than-staggering energies and dwindling federal support for many of the programs they must manage.

It will be up to Mr. Downs to get the most possible value for the public dollar in services pinched by tightened budgets. Mr. Touchstone will have broad jurisdiction over much of the physical shape of the city, from environmental services to transportation and the functions now carried out by the department of general services. These responsibilities affect a lot of people directly and daily. If things go wrong, the complaints can add up to a major indictment of the city administration.

At least until the next blizzard, breakdown in garbage collection, rash of potholes or bureaucratic snafus, Mr. Downs and Mr. Touchstone will enjoy the city's good will.