William A. Lubbers, general counsel of the National Labor Relations Board, upheld yesterday the major league baseball players' contention that the owners have failed to bargain in good faith.

In authorizing the issuance of a complaint of unfair practice on the players' behalf, Lubbers may have provided a key to unlocking the stalemate that had made a strike on Friday seem a virtual certainty.

In filing the charge of unfair labor practice with the NLRB, the Major League Players Association contended that the owners had failed to bargain in good faith by insisting that compensation for free agents -- the only issue -- was essential to the fiscal health of the game but refusing to turn over documentation to support that claim.

Lubbers will decide today whether to ask the NLRB for permission to go to U.S. District Court in New York City seeking an injunction that could extend the strike deadline for 30 days and could compel the owners to turn over their financial records. The extra time would allow the union to use the data in bargaining sessions.

Before the decision was announced, Yankee pitcher Rudy May said, "I do know one thing. If the NLRB says, 'Okay, boys open up the books,' they're not going to do it . . . Do you think Gene Autry wants George Steinbrenner to know how much he's making? Do you think George Steinbrenner wants the rest of the 25 clubs to know?"

Marvin Miller, the executive director of the players association, said, "The issuance of a complaint is a finding by an impartial government agency, after investigation and hearing both sides, that there is reasonable cause to believe they have violated the law.

"It is a finding that the 24 (U.S.) clubs and the players relations committee have attempted to mislead everybody," he added.

Ray Grebey, the chief negotiator for the owners, who had not seen Lubbers' statement, said, "We believe that there is no merit to the compliant and that the players association is not entitled to the information it seeks."

Grebey has insisted continually across the bargaining table that the issue was never one of financial need on the owners' part or inability to pay.

Lubbers agreed that financial considerations had been injected into the negotiations by the owners. That was a crucial factor in his finding.

Joseph D. Norelli, deputy assistant general counsel, said, "The owners are the principals. Ray Grebey is their agent. When a principal makes a statement, it is questionable whether the agent can disavow it."

Lubbers has, in effect, become a prosecutor on the players' behalf. Don Fehr, the general counsel of the players association, likened Lubbers' action to a grand jury returning an indictment. "He has said there is sufficient grounds to go forward," Fehr said.

But Lubbers can go forward in several different directions. He can refuse to seek the injunction requested by the players, which would mean that the case would be brought before an NLRB administrative law judge, often a lengthy procedure.

George Cohen, a Washington attorney for the players association, said that the owners would be under no "enforceable compulsion to turn over the financial data" until a judge ruled in the players' favor.

The players sought an injunction in order to hasten that process.

If Lubbens decides to seek an order for an injunction, his decision must be approved by the NLRB. If the board, which currently has only three sitting members instead of five, grants the request, Lubbers could then seek a court order in New York to compel the owners to turn over the financial data, extend the strike deadline 30 days and prohibit the owners' compensation plan from becoming operative in October unless they bargain in good faith.

"Theoretically, a judge could grant the injunction within 24 hours," said NLRB spokesman Thomas Miller.

The negotiations will be resumed at 2 o'clock today in New York. Asked what effect Lubbers' decision would have on the talks, federal mediator Kenneth E. Moffett said, "I don't think both sides will be doing much bargaining until they see which way the NLRB will go. I expect both sides to be there, but I don't know how much will be accomplished while the specter of an NLRB decision is hanging over their heads." Representatives of both sides met yesterday for 2 1/2 hours in New York but accomplished little.

Some sources close to the negotiations speculated that Lubbers' decision will prompt those owners who are opposed to the strike, and those who might be wavering, to pressure for a settlement. Others suggested that Lubbers might have prompted a settlement because the owners would rather capitulate on the free agent compensation issue than hand over the financial data the players have requested.

In Baltimore last night, Orioles owner Edward Bennett Williams said, "I've always felt that reason will prevail over lunacy before Friday and I still believe it will."

Doug DeCinces, the American League player representative, said following the O's 6-4 victory over the New York Yankees:

"This could keep their strike insurance from kicking in and it should. Their whole idea was to get strike insurance, not negotiate seriously, then collect their millions.

"The best that they can get (out of the bargaining process) changed a whole lot today.

"This should make clear to the average fan that it is not the players who are creating the problem."