WHAT RONALD REAGAN needs most to redeem his shredded arms control policy is a main player of the caliber of William D. Ruckelshaus, who was brought back from the private sector to become, again, director of EPA.

Reagan vehemently resisted the change at the top of the polluted agency. He protested from the beginning that Anne Burford could not be improved upon. She had a "splendid record," he said, as his staff busily plotted her exit. When time had run out, he was insisting that faceless pygmies who shouldn't be able to look at themselves in the mirror had forced her out.

While plainly bowing to political pressure, much of it generated by his closest aides, he was pathetically claiming that he always stood up to it. It was an incoherent performance, which left a swirl of questions: If she had indeed been so peerless a public servant, why did he cave? Would it not have been more manly to face down the snipers and their "unfounded allegations?"

His angst arose from the fact that Burford had been doing his bidding, believing as she does, that EPA picks on big business. The conclusion he forced on observers was that some illegality occurred in the furthering of his philosophy.

Such is his luck, however, that, in spite of himself, he got Ruckelshaus -- and the noisome EPA story off the front pages.

Rucklelshaus is one of those men who is infatuated with public service, but not to the point of hanging on to high office at any cost. His conduct in the October massacre of 1973 put him in that small pantheon of American officials who have resigned on a point of principle. After Elliot Richardson resigned as attorney general, Ruckelhaus, his deputy, was next in line to fire Archibald Cox. He refused and quit. His return to EPA is a major coup. But even when Ruckelshaus stood beside him, having accepted the appointment, Reagan was complaining that criticism of EPA had been "unwarranted."

Reagan confronts a comparable personnel crisis in arms control. His nominee to head the Arms Control and Disarmament Agency, Kenneth Adelman, stands revealed as having "misled" -- "lied to" has been carefully avoided in the discussion thus far -- the Senate Foreign Relations Committee in regard to the egregious memo from Reagan's chief negotiator in the Geneva talks, Gen. Edward L. Rowny.

Rowny is to arms control what Anne Gorsuch was to environmental cleanup. He may not be doing what is indicated by his office, but he is plainly doing what the president wants. He is "standing up to the Russians." But the memo shows a man of such small- mindedness that you wonder if he could manage a two-car funeral, much less negotiations on strategic nuclear weapons.

The president's defense policy speech, complete with a satellite photograph of the runway at Grenada, and a Buck Rogers plan to transfer the arms race to outer space, was made the night the memo was made public. Together, they reaffirm what has been apparent all along: that Reagan will do anything to avert the nuclear freeze and to avoid negotiating with the Russians.

The release of the Rowny memo, which the general originally disclaimed, has him indicting three members of his five-man negotiating team for favoring "progress at any cost."

He is, in short, discredited. No matter what Reagan comes up with next week in the way of a new bargaining position, it will be a waste of breath as long as Rowny is at the table.

Reagan has voiced as much confidence in Rowny -- and Adelman -- as he did in Burford. But reality, in the form of squawks from Capitol Hill and Europe, may yet intrude.

Reagan was unfurling a nuclear umbrella he proposes to raise over the country sometime in the next 20 years -- in flagrant violation of the ABM Treaty, which he opposed anyway. But as he did so, the Democratic budget, which easily passed the House, spoke directly of resistance to his defense spending and indirectly of malaise with his disarmament stance.

If Reagan is finally driven to sending in a substitute, he could do no better than Ruckelshaus' former boss, Elliot Richardson. Richardson is the most portfolioed of all the Nixon-Ford alumni, to whom, as David Broder points out, the president often turns to in the crunch.

The former secretary of almost everything is now a Washington lawyer, and in disregard at the White House for his vigorous advocacy of the Law of the Sea Treaty, which he negotiated for the U.S.

Like Ruckelshaus, Richardson has an insatiable craving for government service, but not at any cost. If he should go to Geneva, the public will be assured that he is going there to negotiate an accord with the Soviets that would reduce the threat of nuclear war.